synthetic oil change
 

I like the idea of using synthetic in my turbo D, but just when should I pour it out and bring in the new? My driving is almost all highway and 3,000 miles only gets me six weeks. Filling the 2 gallon crankcase that often would run into real money pretty quick.

The long answer is: have the oil analysis done and change accordingly. Many have posted that they show 10k and more between changes is fine by analysis.

Do a search on synthetic oil on the site, should be a TON of stuff on that, empirical and anecdotal eveidence abounds that you can extend your oil changes by double or more, hopefully more, especially with your mostly freeway driving, so the synth works out to be more economical for you than dino.

Short answer: Change every 6-8k.

Peashooter,

I've been using Mobil 1 15W50 for 13 years in my '80 300SD and changing the oil and filter every 10,000 miles with no noticeable wear on the engine at 250,000 miles.

Others have has oil analysis done with oil used for 10,000 miles and there were no parameters that said the oil needed to be changed more often.

I know there are some that say change every 3000 miles but that is old thinking from when synthetic oils were not available. With your type of driving, changing oil and filter every 10,000 miles is sufficient when using synthetic oil and that will make the use of synthetic oil more economical. Watch for Mobil 1 or Shell Rotella synthetic specials at Walmart.

P E H

I contacted MB and asked about using synthetic oil in my 83 and 94 diesels and they said the engines were not designed to run on synthetic oil and I should not use it and gave me a list of oils that were approved. Are they wrong I called Mobil and asked them and they said use whatever MB recomends. Amsoil said the same thing. Are they wrong?

That's funny, Mobil 1 15W-50 is on the approved list in the owner's manual for both my brother's 300SDL and my 300D -- however, the 10W-40 is NOT on that list, and there is a not that says don't use any 10W-40 in the diesel.

Delvac 1 would be a better choice if you can find it.

I go 6-8000 miles on a change, never had a problem.

Peter

Here's how to translate anything that MB states.

If the vehicle in question is still under warranty, use what MB recommends.

If the vehicle in question is NOT under warranty, use what people who have hundreds of thousands of road-test miles behind them say and use the synthetics.