What oil to use - Page 2 - PeachParts Mercedes-Benz Forum

torsionbar · #16 10-17-2017, 10:16 AM

Quote:

Originally Posted by cmac2012

But I've heard discouragement on the going with synthetic angle.

It is common internet lore that you can't switch to synthetic on an older car or it'll cause leaks. I've not found that to be true. Have owned a number of cars older than me, and ran synthetic in all of them. Synthetic will exacerbate existing leaks, but I think some folks confuse this with "causing leaks". The leak has been there, the synthetic oil just helped you find it.

Even the '59 beetle I had that was sitting for 20+ years before I fixed it up, I ran synthetic Red Line 10w30 in it for more than 25,000 miles, in all four seasons, before I sold the car. After replacing the various gaskets that had visibly been leaking for many years, the engine was tight and dry with the modern synthetic oil.

BillGrissom · #17 10-17-2017, 01:17 PM

If I was the PO, I probably wouldn't have answered either since you seem overly concerned and fussy, so no answer might have satisfied. Haven't you seen "semi-synthetic" oil blends in the auto parts? Doesn't that refute any rumors about "can't mix oils"? Diesels put more carbon into the oil than gas engines, so need more detergents to suspend the carbon between oil changes. That is the reason for diesel-rated oils "CJ" and such. Many classic car owners use diesel oil in their gas engines because some have higher zinc content (protects flat tappets and especially solid lifters like your engine). Since the oil blackens up faster, best to do regular oil changes say 4000 mi tops, so the main feature of "longer changes" from synthetic oil is mostly wasted. My opinion is regular oil with frequent changes is better than synthetic with longer changes.

If you want more important things to worry about, wonder when your vacuum pump's innards will come apart and slide into the timing chain, or when the power steering belt cuts into an oil cooler hose or those hoses just burst on their own.

Redcamel · #18 10-17-2017, 02:35 PM

Of course I'm concerned, I don't want to damage the car by making a mistake. I'm not a mechanic or even close to one so in order to not make a costly mistake I felt the best route to take would be to join a forum where people with more experience and skill can help guide me away from said costly mistake. Hope I'm clear on that. The Fussy part I'm not sure about, I'm pretty easy going, you seem to be the fussy one. But anyways I sure do appreciate all of your replies and sound guidance. I have another issue I'm contending with. The valve cover has a gap in the rear when it's torqued to 10 foot pounds. Have a great day.

Diseasel300 · #19 10-17-2017, 03:27 PM

When the valve cover has a gap when torqued, it usually indicates that it's been overtightened in the past and is now warped. There are a few threads here about people straightening them by sanding on a flat surface. Probably easier just to replace the thing.

My own $.02 on the synthetic oil debate: I don't really care one way or the other. There are synthetics out there (Delvac) that are roughly the cost of conventional oil. I do notice an extra "eagerness" from the SDL when running synthetic, especially when cold. I run full synthetic in the Honda, running conventional you notice a rough idle after ~2K miles and noisy lifters around the 3K mark. Synthetic will last a 5K OCI (I never run it longer than that).

Redcamel · #20 10-17-2017, 04:03 PM

Hi Diesel3000
As far as he valve cover goes, I just looked at the shims and one has been broken or warn shorter than the others. also, the inside measurement of the valve cover from lip to ceiling, corresponding to the height of the cam chain, is to short! When I place the valve cover on the head without the gasket the chain hits the ceiling of the valve cover and the valve cover does not touch the contact surface of the head, there is a gap. when I replace the gasket on the valve cover and re place the valve cover on the head it still does not seat in the rear.

I remember a couple times in the past I've heard that you shouldn't add synthetic to older cars with higher mileage but the more digging I do the more I read about people having good experiences with synthetic in old cars.

Redcamel · #21 10-17-2017, 04:06 PM

Sorry Diseasle300

Diseasel300 · #22 10-17-2017, 05:48 PM

Quote:

Originally Posted by Redcamel

I remember a couple times in the past I've heard that you shouldn't add synthetic to older cars with higher mileage but the more digging I do the more I read about people having good experiences with synthetic in old cars.

A lot of that comes from the early days of synthetic oil. In the 70s and 80s synthetic oils were something you had to treat with kid gloves. Mix different brands or conventional oil and you could wind up with foaming or some serious gasket/seal leaks.

The modern stuff? Not so much. I run synthetic in the SL and it actually leaks LESS with it than it does with conventional. The SDL gets whatever is on sale. Sometimes it's synthetic, sometimes it's conventional. It doesn't seem to care.

Modern synthetics can be mixed with each other or with conventional oil. They won't foam or attack seals like the synthetics of yore did. If you live in a cold climate, your engine and starter will thank you if you run synthetic at least during the cold months.

Redcamel · #23 10-17-2017, 05:57 PM

Diseasel300 I do live in a cold area as a matter of fact it's cold right now. Been dipping into the freezing territory at night. After I fix this valve cover issue I think I'll give synthetic oil a shot this winter and see how she does.
Are your cars both high mileage?

Diseasel300 · #24 10-17-2017, 06:18 PM

The SDL is the highest mileage car in the family. It just clicked over to 179K yesterday. The SL is at 116K, but does tons of sitting, which isn't good for it. The Honda isn't even broke in yet. SDL is due for an oil change soon and will likely get synthetic for the winter. It doesn't get that cold here, but when I drive it to work, it isn't a long drive and I'd prefer the better lubrication at cold temps.

Oil is one of those personal preference things. As far as I'm concerned, there is no right answer. Use what you feel is right. Any oil that's changed on a routine should be fine. I'm not a fan of extended drain intervals. You see lots of people stretching their oil out to 10K miles and doing oil analysis to see how long it'll go. Not my thing. 3K in the diesel, 5K in the gas.

Larry Delor · #25 10-17-2017, 07:16 PM

Quote:

Originally Posted by cmac2012

Ho boy, and how. I'm tempted to go with synthetic ('86 300SDL), if indeed I can go 6 to 7 thousand between changes and filter. If the oil costs twice as much, I'm money ahead. Not to mention less work. My previous daily driver, an '87 BMW 325i, had synthetic it's entire life. I'd change at about 7500, 5.5 quarts.

But I've heard discouragement on the going with synthetic angle.

I remember that the oil was just over a buck a quart (if you bought a case) when I used to have the 300D.
Now, I have the TDI, and it uses some sort of überöl - super duper synthetic, and oil changes are every 10k! That oil is over $10/qt. By the time I figure the oil and filter, I'm looking at $50. The local dealer usually has a $20 coupon, so the bill there is usually around $80, plus they check it out, and give it a bubble bath.

rocky raccoon · #26 10-17-2017, 07:54 PM

Red, get a straightedge on that cover to see if it is actually warped. If it is, you will probably find several on ebay at reasonable prices. Any year OM617 cover should fit
including non-turbo.

Also, the gasket is one of the rare cases where Genuine Benz is far better than aftermarket. It fits to the cover more tightly and is less likely to be displaced when installing. One more tip; removing the cruise control actuator (easy) will allow the cover to drop more easily into place thus eliminating the manipulation that tends to displace the gasket.

OM617YOTA · #27 10-18-2017, 03:49 PM

Maxbumpo posted this awhile back:

https://www.blackstone-labs.com/Newsletters/Gas-Diesel/July-1-2017.php

Summary - run whatever name brand oil of the correct spec you want. There's barely any difference between them.

I run 5w-40 synthetic year round in my 617 because it helps with cold starting vs 15w40 dino, and only run enough miles to change once a year. If I changed often enough, I'd run dino 15w-40 in the summer. If there was a 5w-40 dino oil available for less $$ than synthetic, I'd run it happily.

Seriously, whatever's cheapest. For our uses, effectively the only difference between the oils is in your wallet, not the engine.

ah-kay · #28 10-18-2017, 04:20 PM

Quote:

Originally Posted by OM617YOTA

Seriously, whatever's cheapest. For our uses, effectively the only difference between the oils is in your wallet, not the engine.

Can't agree with you more. X2

Diseasel300 · #29 10-18-2017, 09:19 PM

Quote:

Originally Posted by OM617YOTA

Seriously, whatever's cheapest. For our uses, effectively the only difference between the oils is in your wallet, not the engine.

x3

As I said above, I tend to buy whatever is on sale. The engine doesn't really care. I tend to go for a synthetic 5W-40 in the winter primarily due to short driving habits. Brand doesn't matter, whatever is cheapest per quart.

Redcamel · #30 10-18-2017, 09:48 PM

Ok if that's what you guys are doing and having success with then I'll follow suit. Also the valve cover is straight. The shims were flush with the bottom so I filed them down .064 and it fit on fine and no oil leaks! So now for the oil change and after that I have to chase down the shifting issue. Shifts like a sledgehammer into 3rd, ridiculous but I Bought all the vacuum and transmission stuff from ************** who have been great so far.