126 V8 Oils
 

Recently acquired 500 sel had 10-30W synthetic engine oil according to p.o. It also came with massive oil leak from lower oil pan gasket. Upon replacement of oil pan gasket should I stay with synthetic oil but heavier weight 20-50W? or go back to conventional Rotella Diesel 10-40W that I used successfully in a 450sel? or perhaps try new Rotella Diesel Synthetic? Am I throwing money away staying with synthetic on a 140,000 mile engine? Recent article on this board about engine oil for older engines didn't resolve issue for me.

If the engine is running well with no leaks, I see no reason not to use the 5W40 "synthetic."

I'd run 20/50.. Esp. if you Drive the car at all. Mercedes calls for heavier oils in these cars.

More importantly is the additive package in the oil you are running. Most of what's out there is not what the Engineers had in mind when your engine was designed.

Jonathan

in my 84 500sec i was happy with mobil 1 10w30.

tom w

For Dino, go any old 15W-40...
 

...as in Delo, LongLife, Rotella, etc.

100% Synthetic Amsoil AME 15W-40 is easily a 15,000 mile oil in these cars: just remember to change out the filter at 7,500, at the very least.

I change my filter every 5K, top off & I'm good to go!:D

Cheers!

In my 4.5 i stick with 10w30 or 40.
I found 20w50 WAY too thick and I wouldnt think of 5w30 in an engine I drive that hard and gets that hot.

I would go with 10w30/40 in any m116 or m117. People tend to put in thicker oil in these and it winds up putting a lot of sludge in the cam oiler tubes, cutting off vital flow.

20/50 if you look in your owners manual covers a wide range of temperatures. I would run 10-40 in winter living up north, but most def. not in summer.

Not sure who told you 20/50 clogs your cam oiler tubes with sludge, but the weight oil you run has absolutely nothing to do with sludge. How often you change it, how hot your engine runs...that has direct effect on sludge.

All of my cars run either 15/50 or 20/50 and I can promise you they are as clean as can be.

Jonathan

cdplayer
 

I agree. Living out West, summers can be brutal. My mech recommended 20/50 on my car just because of the high miles (currently 234,000).
Helped to improve compression. So I went one step further and put Mobil 1 20/50 right after I got her.
Boy, does this stuff clean out your engine. Cleaned so well, began noticing oil leaks.
After 5000 miles, I went back to Castrol 20/50 (dino oil) for high mileage engines.
This oil has additives that actually swell those tired gaskets and slow down(or stop) those pesky oil leaks.
Cured my leak problem after 2000 miles.

What he said!

Look at your owner's manual and stick with what the engineers who designed your engine recommend.

After reading a lot of oil discussions here, I keep falling back on the principle of RTFM. My manual is quite clear on viscosity--20-50 is the recommendation for the temps I drive in with this car (3-season only). 5-30 found its way in there once by error and consumption went way up. MB obviously had certain characteristics in mind in designing the engine, and set their recommendations to match them. Re oil type, the best performance I've had re leaking at 165K is dino old-engine formula, Valvoline in my case, so I'm stickin' with it. For this high-mileage beast with no top end work done yet, and not much needed, frequent changes seem more key than high-tech chemistry. But that's my answer for a high-mileage seasonal-use car--your situation may be different, and it's always "horses for courses".

I agree with you. I recently bought a 1991 300CE with 120k miles on it. After I bought it I had all the fluids changed, including the oil. I decided to try Mobil 1 5-30. Big mistake. Oil comsuption went up way high.

Went back to dyno 2-50 and oil consumption dropped down to a little less than a quart every 3k miles. Which is pretty darned good for a high compression engine with 126k miles.

Stick with the info in your owner's manual; look at the detergent qualities of the oil you use and change it often. Dino oil is cheap, and engine overhaul is expensive!

I run Delvac 1 5w40 in my old diesels and it seems to work great, I would think the gas engines of similer vintage would like it as well. According to my 603's owners manual 5w40 is recomended for just about all temps.

I've seen more than one MB V8 suffer from cam oiling issues when using heavy weight oils. Its not a sludge problem but more a problem of squeezing enough cold thick oil thru the small cam oiler tube holes. May be OK in warmer areas but I wouldn't do it here in Texas in the winter.

I run synthetic in my V8 cars.

However, I read somewhere that you never have to change your oil.:rolleyes: