Synthetic oil debate - PeachParts Mercedes-Benz Forum

SHARK1007 · #1 10-22-2002, 09:26 PM

I thought I had figured it all out until today. I had decided to switch to synthetic at the next change. I just bought a 1983 300SD with 160K, very well maintained till last 2 yrs ( all records) and then reasonably maintained till now by frugal owner, oil changes every 5K.

I have the car at Ron's European in Merritt Island Fl., he was recommended as a very experienced "whiz" who occasionally solves the dealer's problems. 30 plus years experience.

I asked him about synthetics and he said no way, that the gunk it cleans out from the motor will fall to the oil pan and clog the oil pickup screen, potentially causing catastrophic failure.I had the pan off and it didn't look too bad.

The car seems clean, I'm bringing everything up to par. Very little blow by and minimal smoke, less than the new 1984 I had in 84.

Now what?

engatwork · #2 10-22-2002, 09:29 PM

Sounds like Ron offered you some good advice. Just stick with a high quality dino based oil rated for diesels and you will be fine.

diesel don · #3 10-22-2002, 09:32 PM

If you're in FL, no reason to switch. The only reason I run the expensive stuff is for an easy spin in the dead of winter.

Don

SHARK1007 · #4 10-22-2002, 09:32 PM

I guess you're right, it would scare me to run synthetic after that warning.

Sure sounded like a good idea at first, thank you.

Roger

lrg · #5 10-23-2002, 01:08 AM

I'm not sure I buy his arguement. In a very poorly maintained car maybe but since the oil (any oil) is designed to keep most of the goodies in suspension, I don't think you'll get enough fallout to clog the screen. If you are that worried just change your first load of synthetic after a couple of thousand miles. I'm not trying to start yet another oil debate here, just weighing in that I think your mechanic is worried about a problem that likely only happens in very extreme cases, if at all. I would bet that most of the cars here that are now running with syn oils spent their first 100K or so miles on dino oil and I have never heard of a catastrophic failure from a clogged oil screen. It just doesn't make sense that that is a real problem.

RSH · #6 10-23-2002, 01:48 AM

I also have a 83 300SD, it has 228K miles all the service records were with the car when I bought it. The oil was dealer changed every 3K since it was new with Castrol 20/50 GTX. I mentioned thats what I still use and people here got excited like it was the worst oil you could use in a diesel.My car runs extremely well and has no problems,my thought is why change what has been working.If you know the past service record of your car stay with what has been working, its been running almost 20 years.

Dusty-NZ · #7 10-23-2002, 04:02 AM

Yep ,, my mums neighbour bought his 240D new in Germany and drove it home , well , apart from the bit that had to be on the ship ,

, used only Castrol GTX ever since 1974 ,, he retired in 1990 and decided to give the car a check over , so it would last him out ,, needed a set of exhaust valves and a chain tensioner ...... had done 609000 ! Well it got rings and bearings too , but that was just 'cause he had it pulled down . Biggest job has been keeping the body sound .
My wifes 300D has always had Shell Rimula 30 , 'cause that was the fleet oil available on tap .......... 355000 so far ,, did the glow plugs a couple of months ago ,, all's well , though reading this forum has me worried I ought to look at the valve clearences ,, I've no record of when they were last done ,, more than 100,000 ago .

Hot running is important for long engine life ,, that and regular oil changes .

stephenson · #8 10-23-2002, 12:29 PM

Just an opinion ....

Whiz sounds way out of date - good statement coming from his grandfather perhaps.

Search for better opinions (well, you may feel this way about mine ....).

#9 10-23-2002, 01:09 PM

Three things I believe are "relatively" true about synthetic oils based on all that I have read:

1) mercedes uses them in their new vehicles;
2) they are more durable and therefore offer longer oil change intervals;
3) they tend to stay on the engine parts longer and provide easier starting/quicker lubrication;

For these reasons alone I use Mobile One. The notion that using synthetics in old engines will create problems (loosen sludge and/or make leaks) is not new. I've heard much the same about transmissions in old tractors..... I just have a hard time not using the "best" product available in my very special old machines.

Nic
'85 300CD @ 154k miles

psfred · #10 10-23-2002, 07:38 PM

Synthetics will indeed "scrub" the engine, but the crap will all end up in the oil filter.

Hans does not use synthetic oil in diesels because he feels it gets too thick with extended changes. If you want to use short intervals (3K miles) there is no advantage. After all, my work van (92 Chevy V6) has had the oil changed every 3K since new, and has 299,000 miles. Runs like a champ, has never had any engine work. If a piece of junk like that will live forever on dino oil, so will a Benz. You just have to change it every 3000 miles.

However, synthetic oils are vastly superior oils, by any way you want to measure them. If you use a CH-4 rated oil, you can easily change once a year if you want, and the engine will last forever if you don't overheat it. Certainly 6000 mile oil changes (my plan) are fine.

The only difficulty you will have is the junk in the oil filter. If you do change to synthetic, change the oil filter again after 1000 miles and you will be fine.

Peter

jay123 · #11 10-24-2002, 06:02 PM

If you had oil leaks before using syn oil, they will be worse after you switch to it.

Everyone should take a look at this link and read ALL the info:

http://www.carjunky.com/news/motor_oil_myths.shtml

It is very good !!!! Answers all your ??? on syn oil and dino oils and snake oil additives...

rickg · #12 10-24-2002, 06:17 PM

Thanks Jay123! Finally an unbiased opinion form an outside source. I have avoided this whole thread because I knew how these debates go (or don't!). But decided to take a peek and see how it was going.

jay123 · #13 10-24-2002, 06:47 PM

I'll tell you, Rickg.. Everyone here at this forum all have personal experiences and opinions on all things. Everyone is also very helpful.
However, not everyone's facts or info may be correct. It is always good to do your own research.

Glad I was able to help...

psfred · #14 10-24-2002, 08:12 PM

Jay:

Synthetics don't leak any more or any less than dino oils -- they have significantly higher viscosity hot, so leak less then. They contain seal sweller/maintainer compounds -- this is the source of the "synthetics make older engines leak" -- the old (1970s) synthetic rubber seals would indeed shrink if they were used for a long time, and only the scale and varnish from dino oil kept them from leaking. Remove the varnish, and dribble......

Problem was fixed from both ends -- better sealing materials have been used for at least 20 years now, and the seal conditioners were added in 1974 to Mobil 1.

This is a very old myth, and not true. Some engines may leak more, but I've cured slow leaks on several with synthetic oil. My 300D uses about a quart in 8000 miles (all leakage at the front chain cover), the 300TE still uses a quart in 2-3000 -- all leakage at the front chain cover, and I've seen no leaks so far on the 280. The work van went from a quart in 400 to a quart or less in 3000 after I put some sythetic in it. All depends.

Certainly a leak will cost more if you use the synthetic, since it costs about twice as much. I've never heard of a good engine springing massive leaks on sythetic, though.

Peter

rickjordan · #15 10-25-2002, 12:06 AM

If you are concerned about the sludge, just look under the valve cover. This is where any sludge would build up. If there isn't any sludge there, then don't worry about it.