Never use synthetic fluids in your old diesel!!!
 

"Never put synthetic oil, transmission fluid, or differential fluid in it.... if you want to start having problems, just start using synthetic fluids... they loosen up stuff that shouldn't be loosened and that car wasn't designed for use with synthetic fluids."

Those were the words of my mechanic when I mentioned to him, the fact that I intend to use Amsoil synthetic fluids bumper to bumper in my 1984 300SD. I searched all over the forum and spent about 40 minutes browsing through search results and I've seen nothing but praise for Amsoil's synthetic oils and ATF. He really confused me because I had put Amsoil fluids in my 1989 Mazda 929, my 1990 Honda Civic and in my 1999 Toyota Avalon and they all run well without any issues. Additionally on the Amsoil website it is stated that the diesel oils they have a suitable for use in Mercedes-Benzes. But then again, my Mazda and my Honda have been using the fluids for over a year but I've only put on about 4,000 miles on each of them (they aren't daily drivers... just cars I bought to have for fun). I've never had any problems, or ever heard of synthetic fluids being bad for ANY car.

So right now, I am thoroughly confused and I'd greatly appreciated it if someone who has been using synthetic fluids for lots of miles spoke out to help clear my mind!!:confused:

oh man - if you only knew how we feel about oil threads:eek:.

welcome aboard

Two oils for these cars

Delvac 1 synthetic

Delo 400 dino

These are the only two oils you should consider for a diesel. I swapped my 300SD over to Delvac 1 at around 79k and I have not had any issues whatsoever with leakage or usage.

I run Delo 400 in the 300D's because I already have some leakage issues that I need to address over the next year or so.

I use Mobil 1
 

fully synthetic in my cars and trucks and no problems..your mechanic is nuts..

I bought my 1983 300sd new, it came with 4 years or 48,000 miles warranty. I used it as a daily driver. A few years ago, when I could find Synthic oil at walmart for about two times the price of normal oil and my 300sd had over 100,000 miles on it, I swiched.
My 300sd is still my daily driver and has 230,000 miles on it. It get 26 to 30 mpg and has pick-up and go.
I change the oil and filter myself every 3,000 mile and it does not need any oil in that time.

When I have to use a rental or my wifes Volvo, I love the 300sd more!

I may not need to change the oil every 3,000 mile but I look forward to it.

yeah, sure
 

Like what exactly?

Yeah, I've heard this before. And in hopes of avoiding an all out flame-war, I'll just say this: If you have crap stuck to parts of your engine, perhaps you aren't changing the oil frequently enough.

I forgot to say I have been using Rotrlla T Synthetic 5-40. Walmart $12 or $13 an gallon. I have not used synthetic ATF but change that my self every two years. Original engine and tran.

Many years ago detergent oil was not widely available and most just used plain old SAE 30, non-detergent. For those who switched to the new detergent oils that had already run many miles on the old non-detergent, engines began to blow up because the detergent oil statred to loosen up all the crud in the engine and clog oil passages starving bearing.

So the old adage was, never put detergent oil in an engine that had always run on non-detergent! And that still hold true today and you can still by non detergent oil.

Sounds like your mechanic is confused!

I haved used Amsoil products for over 20 years. I first started using it in my Suzuki PE250 Dirt Bike. The bike used to foul plugs like crazy. Somebody suggested using Amsoil two-stroke oil in it. I tried it and never fouled another plug. To this day I use it in chain saws, weedeaters, leafblowers etc. They all seem to start easier and run smoother. I used Amsoil in my 81 240D with 240K. It seemed to run smoother and quieter. I never had one problem with anything loosening up inside the engine. I also had a friend of mine had a Ford F-350 that wouldn't go into first gear when it was cold out. He changed the transmission fluid with Amsoil. Never had another problem getting into gear.

Andy

While we are on the Amsoil topic, I think I'm going to switch to it on my next change, it is more availible in my area. Delvac one is impossible to find. What type of Amsoil do you use in your MB? I would like to use a 15w-40 or 50 in the summer and a 5w-40 or 50 in the winter. Do they have these weights?

Before switching an old engine to synthetic, a good cleaning is a good idea.
Check out auto rx ( www.auto-rx.com ) the stuff is costy, but it really works. I've been using it on my own cars and my customers cars for awhile now with great results every time ( I have no affiliation with them, their stuff just plain does what it says it does. I sell and install amsoil products out of my shop, but this is the cleaner that I use)I've averted a number of seal repairs with that stuff..

This is my two cents on engine flushing. Before I do it on a Mercedes diesel I drop the oil pan and clean up any sludge. I then paint the inside of the oil pan with either Glyptal (available from Eastwood) or POR-15. I then reinstall it and of course replace the oil. At the next time it is due for an oil change I flush the engine. If you have a lot of sludge in your oil pan an engine flush can cause too much debris to go to your filter which in turn clogs it. Then you have that extremely filthy oil which is not filtered circulating. By painting the inside of the oil pan the surface becomes too slick for deposits to form causing it to be picked up by your filter. Just be careful during future oil changes cause it really shoots out when you remove the drain plug. By the way Amsoil is available online with direct shipping to your door.


Andy

is it really necessary to have synthetic oil ? i change the oil every 3k miles religiously (filter also)..... isn't that enough ?

i use Rotella 15-40

I've had similar results with Seafoam, although admittedly I haven't taken an engine apart yet that I've used SeaFoam on (operative word: "yet"...my truck's engine's partially coming apart soon and I'll see the rearl results). You can get a can of Seafoam for about $6 at Napa Auto Parts. I add one pint into the oil a few hundred miles before I plan to change the oil.

With the truck, after treating the oil like this twice or three times, the oil would actually look clean after almost 3000 miles of use. I was shocked the first time I saw it as well, but it seems to really work. But, time will tell for sure when the engine comes apart (doing head gaskets and lifters)...hopefully within the week. :)

BTW, on the synthetic issue, I'm one of the people who's scared by the theory of seals swelling up with new oil and developing leaks where there were none before. This is the only thing stopping me from using synthetic in my engines, and I am already using synthetic in the Benz's differential and in the truck's tranny and transfer case (and when I do a differential oil change on the truck, or a tranny oil change on the car, I plan to go to synthetic). Synthetic's more refined than dino oil, and I also like the idea of not depending on petroleum oil resources any more than absolutely necessary (and am looking into a WVO conversion for the same reason). When I put my truck back together, the only seals/gaskets that won't be replaced will be the rear main seal and the oil pan gasket, so I may try synthetic in the truck and see how she does... :)

Personal experience...
 

FWIW, switched both cars over to Mobil's Delvac 1 5W-40 after purchase.
The 617 in the '82 300D had 112K when purchased; no leaks or reported consumption. 30K later, no leaks or consumption between 5K oil changes.
The 602 in the '93 2.5 Turbo had 143K when purchased; no leaks or reported consumption. 25K later and it too remains leak free and does not consume oil between 5K changes.
Summary: synthetic or dino, if the car had pre-exisiting leaks or consumption problems I would look further than the oil selected.
As for oil brand, I'll stick with the majors; ExxonMobil has a demonstrated legacy with synthetic oil technology. Much of the research that went into developing their Mobil 1 line of synthetic motor oils probably helped in the development of Delvac 1.
Just my thoughts on the subject.

Oh I know... as I was doing my research by checking out search results, I saw several threads in which the first reply was something like "not another oil thread"! Couldn't resist joining the party though. :D

Like AndyRM said, Amsoil is available on the web with direct shipping right to your door. I'd like to use either the 10W-40 multigrade oil or the 15W-40 Heavy Duty Oil for Diesel engines. They don't have 5W-40 or 50 though. Just check out this page to see all the Amsoil synthetic motor oils you can get.


Thank you all for your responses. I have been really confused about this. I have a friend with a 1981 Toyota 2.2L Diesel pickup truck and he has been running Amsoil for 19K miles. I was wondering why an old Toyota can run it bumper to bumper with no issues, yet a so-called "super engineered" benz can't. And yet the mechanic that got me all confused has been working on Benzes and Bimmers (the latter mostly though) for 16 years!

So the general solution is as follows: use a good engine flush to clean out any crud in the engine first, then apply synthetic oil.

Why is it so important to clean the inside of your engine?

If you have been changing your oil when you should, there shouldn't be any sludge in your oil pan, and why kick it around if there is?

All you need is one oil port to a rod plugged and you're finished!

If you go with Amsoil, I would suggest:

AME 15w-40 is their full synthetic diesel oil. Many people can use it year around depending on their climate. (Keep in mind there are people using Mobil 1 15w-50 in Northern Minnesota winters.) Its also the most cost effective.

AMO 10w-40. A bit more costly than the 15w-40 and marketed towards gas cars, its CI-4 diesel rated and runs fine in diesels. I know several people using it.

AFL 5w-40. More costly than the 10w-40 and marketed towards Europeans cars, its CI-4 rated. This is a new product.

Regards,

I did a couple thorough dino oil changes on my cars, then switched them to synthetic. I don't trust those engine flush products and IMO they must put too much stress on the engine because they severely reduce lubrication. I just flush my engines with a quart of fresh engine oil at each oil change. This is really effective at getting out a lot of the sludge at the bottom of the oil pan.

I think the idea that synthetic oil will loosen up sludge more than dino oil is a myth. I really doubt synthetic has a greater ability to dissolve sludge. The difference is that it won't add more sludge like dino oil will.

If I remember correctly Amsoil has been around longer than Mobil 1.

Andy

If I remember correctly, Amsoil buys their base stock FROM Mobil. :p

ck42

Right, Amsoil and Mobil use the same base stock. I have been using Amsoil 15/40 for some time. After I rebuilt an "80" engine and put it in my wifes 240d there was a small oil leak from the aft crank seal. Now, 10K and a year later there is NO leak. I switched back to Amsoil when the engine had 1.5 k. I use their 100 : 1 two cycle oil in my power saws. Good product

I'd not bother with an engine flush, but when changing from dino to synthetic, change the oil filter (only, with top up of oil) at about 1000 miles after swtiching. It will probably be full by then, with sludge and varnish released from the engine internals. After that extra filter change, change at 6000 or so intervals with filter change.

On a worn engine, ecesssive leakage is also possible from worn seals "protected" from lots of oil moving past them by crud, but it's likely you will not have this problem on a well maintained engine.

If you already have oil leaks or consumption problems, they may get better or worse, depending on source. If you have excessive blowby from crappy rings stuck with crud, the synthetic may free them up an cure the problem, or it may just "pump" worse. Some seal leakage may be cured by the synthetic as it contains a softner/sweller additive to counteract the shrinkage effect on old, dino oil soaked seals.

The seal shrinkage problem was discovered in the 70's when Mobil (and Amsoil) first started marketing synthetic oils. The seals absorbed the dino oil, swelled, and wore to fit, so to speak. The synthetic "unswelled" the seals, and they leaked. Old history.

My take is that I won't bother with synthetic on an engine that uses more than a quart in 1500 miles as it costs too much, nor do I sue it in an engine that has front or rear seal leaks for the same reason. Otherwise, just change the oil filter an extra time and you will be fine.

Peter

The "MOST" important thing is to change the oil regularly! I also use RotellaT 15-40 and have had good results with it.

I'm very weary of any oil flush. If you have a sludge or buildup problem it's better to drop the pan, clean it and the pickup and change the oil more often with a quality product.

Unless the PO searched high and low for non-detergent oil or never changed it (fairly unlikely on that expensive a car, but you never know!), you won't have an actual sludge problem.

However, dino oils, especially changed on "factory" guidelines (7500 miles) will build up considerable varnish and some hard sludge that will partially dissolve in synthetic oil. This stuff plugs the filter pretty fast on the first filling of synthetic, then is gone.

I use synthetic oil in my lawn movers, too -- reduced the oil consupmtion quite a bit.

Peter

Thanks all again for the responses.

Seems like most of you feel that an engine flush is unnecessary and may actually harm the engine slightly. As a result, I have decided not to use it then.

I've been running it on plain oil and for 2800 miles, it hasn't consumed a drop!! As a result, I'd say I have no leaks. I'll bear your advises in mind as I perform the change.

Now, how about switching to synthetic differential fluid and synthetic ATF? Any comments on that? Thanks!

I have had Mobil 1 75W-90 in my diff for 2k miles and no problems.

Now in the transmission, I don't want to put a new type of fluid in a 16 year old 235k miles automatic. I'm sticking with the regular stuff. Now when I get a rebuilt one, it will get Mobil 1.

Well my MB has synthetic from front to back with no real problems. In the motor first time I ran a semi-synthetic and ever since full synthetic M1. The semi-synthetic did start a leak, one which should have exisisted anyway. It was just loose bolts on the filter housing. I put it in the rear end, it weaped a little before, it weaps a little after. I put it in the tranny and it feels a little less connected than it was before, not really slipping but a little play with RPMs versus speed. I have it in the power steering and brakes with no ill effects. One maybe two problems at most, IMHO well worth converting. As a matter of fact this has been on my mind lately. Some people criticize them because they sound so unprofessional but at .1 microns surely it should help stop the wear. :)

Motor: M1 Synthetic, probably Amsoil after I run my stock out
PS: M1 ATF Syn
PB: Valvoline Dot4 Syn
Rear diff: Redline 75w90 syn
Tranny: M1 ATF Syn
Fuel: mix of #2 and soybean oil (so I guess that is synthetic :))

No Syn for my high milage diesels
 

I have used SYN's in my gas burners but not in my diesels. I have found a VERY good dino oil I like for my MB diesels. BRAD PENN.
Hard to find though. Only find it at small distributers in Atlanta area. It has all MB ratings I guess it is for it's big truck line but when I put it in my 300K SD I add no oil in a 4000 mile change. Unlike other brands. Rotela is the worst for burnning it like fuel.
Goood luck oil is a bad subject here i have never replyed on it and I have over a million miles on all of my cars and I have owned most of them the majority of there miles. Good Luck

I think it is. A C – rated oil changed every 3000 miles with filer is fine.

I switched my 81sd from dino to Mobil 1 Truck and Suv when it became available. I read here where that is repackaged Delvac 1.
This is a high mileage car that has drunk dino forever. Happy to report oil consumption is at a minimum. Ran it over 2300 miles before it used its first quart.
I did do a couple of quick oil changes with the dino to at least try to clean it up first, and I repaired a leaky tensioner gasket before making the change over. That cleaned up my garage floor also.

I didn't mention oil consumption in my last post, but that is because there is no difference. There is no need to add any between changes. FWIW, I changed it over at 183k miles which I'm pretty sure up until then it ran on Castrol 15w40 (most records show this) which I guess is OK. (eBay definition, it works but could be better) :rolleyes:

84 300D, Delo 400 5w40 synthetic in motor, Mobil 1 atf in trans and PS, Mobil 1 in rear diff. 93 C2500 6.5TD, Delo 400 5w40 synthetic in motor, Amsoil 75-90 in tranny, Mobil 1 atf in PS and Mobil 1 in rear diff. 89 VW Jetta 1.6l NA diesel, Delo 400 5w40 synthetic in motor, Royal Purple GL4 lube in transaxle and Mobil 1 atf in PS. No trouble with any of them. Choose a good quality synthetic and don't worry about it. RT

Synthetic Oils
 

Most people think that the best reason to use Synthetic Oils is the extended mileage between oil changes - it isn't. The #1 advantage of Synthetics is their 'film' qualities which allows them to keep an oil film on bearing surfaces and cylinder walls etc. rather than just draining back to the oil pan over time. This dramatically reduces friction wear during initial engine starts. Even if you do change your Dino oil every 3k or less, you cannot duplicate the friction-reducing advantages of synthetics.

Synthetic oils were first developed for cold climate applications where Dino Oils were so 'thick' due to the sub-zero temperatures, you were lucky if the engine would turn over. Under these conditions there was little or no lubrication during cold start-ups so engine wear was very rapid. Synthetics not only flow easily in cold temperatures (another reason to use if you live in colder regions) but the ability to keep the oil film on the metal surfaces really helps reduce wear and aid starting.

Obviously these same qualities will benefit Transmission and Diff's as well.

Andy :)

Here is an interesting oil study.

http://neptune.spacebears.com/cars/stories/oil-life.html

Note that Chevron Delo 400 is a dino oil and not a synthetic. Very good dino oil, though. :p

Well after working on my term report (on bypass filters, maybe I'll post it online here when I'm done too) for tribology (lubrication, friction, and wear) for the past few hours I checked my email to find this. I can't help but find irony in that.... :)

Goldenbear/Chris
You may not be aware but Chevron does in fact make a SYNTHETIC Delo 400 5w-40.... This is not the regular dino Delo. RT

FYI
 

Mobil Delvac 1 is now available at Wal-Mart under the name Mobil 1 Truck & SUV Oil. The price is $4.77 per quart.

I just picked up the last 8 quarts that my Wal-Mart had... time for an oil change. :cool:

The Delo Synthetic is a class III oil as any good dino oil, Mobil Synthetic is a class IV oil. Do the search on the internet for the difference. It is a big differance. That being said, Delo Syn is a good quality oil and will serve you well. It's just that the Class IV synthetic is better for certian applications. I seen many 55 gal drums of Mobil 1 sent to gas turbine US Navy ships over the years.

Synthetic oil was developed by the germans durring WWII for use in the jet engine and further use in all engines do to lack of oil in Germany. Allied jet engines durring this time frame had 30 to 45 minute life span before rebuilding due to lack of synthetic oil. It was about high film strength to protect bearings at 25,000 rpm, and extreme heat range (hot & cold) and a few other minor things. To put it in simple words, no synthetic oil, no jet planes.

Class III or class IV is irrelevant in my case. Since I am not going for extended drain intervals, the Mobil 1 is overkill. I only use the synthetic Delo to ease starting in winter. Put a quart of dino and a quart of Delo synthetic outside overnight in winter and then do a side by side pour test. The Delo synthetic pours much easier, almost like a summer day. Not arguing that the Mobil isn't a superior oil, it is, just double the cost. RT

I think I kind of said that between the lines. It's is all about what meets your needs and leaves you with peace of mind. :cool:

I don't drive that much since I've retired and a 5000 to 7000 mile oil change with high dollar Mobil Delvac 1 is no big deal once a year for me. If I was doing 3000 mile oil changes every 2 or 3 months, I would probably be doing the same that you are. However if you do the use the class IV oil and are able to safely go 2 or 3 times the distance between oil changes then it can even become cheaper to use then a Class III oil. I've never done a 3000 mile oil change on any of my cars in the 30 years I've neen using synthetic oil (Mobil 1) and all have been taken past 150,000 mile with ease. :D Usually I would do 7000 miles before changing the oil, except the '81 Datsun truck which would normally get 10,000 mile oil changes. That truck was well past 200,000 miles and had no oil leaks.

Accusump Pre-Oiler
 

Just curious. Has anybody used a Pre-Oiler system in any of their cars?

A friend with a Porsche 944 race car has an Accusump system fitted primarily to reduce engine damage in the event of a severe oil pressure loss. The system does however have a Pre-Oiler feature which raises the engine oil pressure to normal levels before the key is turned.

He says it is amazing, the starter only has to move the flywheel a very small distance before the engine fires up due to the lack of friction. No churning hot or cold.

Andy

I have gave it a little thought before but never tried anything because I don't want a check valve killing the flow in the lines. Here is a link on a person doing it to a Dodge Ram Cummins turbo diesel.

The distance the starter has to turn it before starting should be the same on a gasser, perhaps if it is cold it could change on a diesel but for the most part this wouldn't change. What would change is the starter could spin the motor faster and with less wear on the starter. Any good synthetic oil should leave a film on the moving parts for at least several days if not longer. (anybody know how long?!)

RT,

Thank you for correcting my erroneous assumption.

Ok, I'm most likely going to change from dino oil to synthetic. I think I read it correctly. After I change from dino to synthetic, I should replace the oil filter 1000 miles after the oil change to synthetic was done, and then every 6000 or so miles afterwards. Correct?
-Joe

No need to do that, unless you think your oil has been neglected in the past. On my 240 I just changed over, then did another change oil and filter 2500 miles later. I have done that several times over the years with excellent results.