I have a 81 300 SD that probably has bad rings. SUcks i know. But as she's still strong I'm ecking as much out of her as possible while I save $$$ to buy another MB. I've been bitten by the bug.

Question being: I normally use Castrol 20w50. After reading everything on this board about oils, I switched to C rated 15w40, however, since this is thinner oil, my extremely high consumption rate (approx. 1 qt every 200-250 miles) was even higher (1 qt every 100 miles). Needless to say, I just switched back, did the oil change yesturday, already seems better, marginally, too soon to tell though.

The guy in the autoshop talked with me about straight 30w oil, thicker than 20w50. I live in the Santa Cruz Mountains, the temp is into the low 30'sF now, and last week we got some 23 degrees, although that's at night and days are still in the 50's and higher.

What do folks think about this 30w oil for this particular application?

Might it help seal the rings a little better?

ALso, he said I could try this product called restore which has tiny copper filings in it, which may melt on the cylinders and create better seal witht he rings. Anyone know about this stuff? Snake oil? Makes me nervous to stick metal purposefully in the engine oil!

Don't use anything like an engine dope. That's for used car salesmen and it only lasts long enough to get the car sold and off the lot.

My personal opinion and recommendation is to try Shell Rotella T 15W-50 and two bottles of STP Oil Treatment. The STP will tend to thicken up the mixture a bit, and is something of a synthetic additive from what I understand.

Besides the rings causing oil consumption problems on these engines, you can also have the turbo bearings wear to the point of leaking a lot of oil. That leakage then goes into the intake and gets burned. Also make sure your crankcase is being vented properly at the connection on top of the valve cover. You don't want that to be restricted because it will increase crankcase pressure and cause oil leakage while running along.

Are you seeing any evidence of leaks? How about an oil slick under the car when you park?

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Look for a C rated 15W-50, preferably CI-4. The non C rated oils that you have been using are probably why you have bad rings.

The 30 weight oil will be much more viscous cold but will be thinner at operating temp. than 15W-40. Not a good idea. Sort of a double negative.

What symptoms are causing you or your mechanic to blame the rings?

The guys over at theoildrop seem to be obsessed with Auto-Rx (http://www.auto-rx.com). If your consumption issues are a result of stuck rings or deposits, this might help.

I shoulda known youall would want the whole story...

April, I bought this 300 SD. Has 300,000 plus. Runs very strong. THe guy I bought it from said it leaked about 1 qt every 500 miles. It had had a top end job a few years earlier. I took it for a pre purchase inspection at a reputable shop with a certified mercedes mech. They detailed some things that needed to be fixed, some possible places the oil leak was coming from, and basically told me this was a strong car, had no blowby, and I should get it. Got the engine cleaned because it was so covered, and then took it in for inspection. They did a valve job, checked for leaks, decided it was burning oil, not leaking that much. They suggested the turbo, or the rings (they checked the vaccuum, it's not that). I got pissed at them at this point, and went to someone else. My turbo blew on the road and I had it replaced, this did not solve the problem. THe new mech ( a good guy) told me I had tons of blowby and should just drive the car into the ground. WE replaced the valve stem guides also. I've been trying Auto RX in it, it's not really helping that much except with the small leak on the oil filler cap. I'm on my first cleanse after my first Auto RX treatment, for 2000 miles, then another Auto rx round. Maybe that the problem was caused by not using the right oil, but I only bought this car a few months ago, don't blame me. I'm bummed on this situation. There are some oil leaks that I probably should try to fix, but they seem small. I've placed a drip pan under the car and only get a few drips a day. So there's the deal. Real ideas will be accepted gratefully.



would it ever be worth it to replace the engine? or should I just get another benz (having a lot more knowledge this time around)?

Learn to do your own work and you can probably find a good used engine for around $750 (around here anyway). If the interior/exterior is in good condition then yes, they are worth saving. If the oil usage bothers you that much and if it comes down to paying someone else to supply/install an engine then yes, find another one and part this one out or sell it.

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Jim

The question of getting another engine is a matter of:

1. How experienced are you at swapping engines? I just recently completed one and it was much easier than anticipated.

2. What shape is the body in?

3. How patient are you to find a cheap engine. They are around.

Don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

If all fails try them:

http://www.remanufactured.com/Mercedes_Engines.htm

Louis.

If these cars aren't disposable, as many here contend, why not just rebuild it and drive it another 200K?

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'91 300D 2.5 Turbo 330K
'00 VW TDI Golf, 190K
'67 BMW R50/2
'73 Norton Commando Interstate