gsaran

I just purcahsed a 1997 C280 with 53K miles on it. Before getting an oil change at a local service shop I reviewed the vehicles records to find the oil type used by the dealer in previous oil changes- which turned out be 15W40. I therefore asked the local service shop to use the same oil. They complied, however they were mildly surprised and mentioned to me that this weight of oil is normally used for diesel engines. The suggestion was to replace this oil by synthetic 15W50 at the next service.

Question: Do I have anything to worry about. Should I get an immediate oil change replacing the 15W40 with synthetic 15W50?
I am particularly worried since the Check Engine light came on a day after the oil change.

Thanks in advance for your reply.

meanie

NEXT oilchange you could go with Mobil 1 15W50.
Check engine light really doesn't have anything to do with an oilchange.

JimPurdy

Mercedes is now recommending Mobil/1 for all models. The check engine light may or may not have anything to do with the oil change. One reason it can come on is if you bought gas and didn't replace the gas cap tight enough. If the gas cap is on correctly and the check engine light comes on everytime you start the car, I would take it in for service.

GDawgC220

Even older models? I talked to my SA at the authorized dealer before and now I've talked to my SA at the independent dealer I go to and they don't recommend syn for older engines because since it's (syn forumla) is thinner, it can leak thru small cracks that normal dino oil wouldn't leak thru....

sph17

If you have a higher milage car that has been run with dino oil, stay with dino oil. If you are down South where it is warm all the time a 15W-50 is fine. Up North, during a cold winter a 15W-50 would be too thick when cold.

gsaran

Thanks to you all. Sounds like dino oil (15W40) should be fine, at least for now.
BTW I live in the SF bay area.

sph17

In the old days there was only single weight oils. As oil gets hot, it gets thinner. An oil that starts out "thick" like a 50 weight oil, as it gets hot thins out to what a 0 weight (or less) is cold.

A 5w-30 weight oil has additives that resist "thining out" as it gets hot. It starts out like a "cold" single weight 5 and as it gets hot, it acts like a "hot" 30 weight oil. All the time, as it is getting hot, it still is "thining" out or decreasing in viscosity, just not as much as a single weight oil does.

If you changed from a petrolium based oil to a synthetic oil, the superior detergents in the synthetic oil may disloge "false oil plugs" that were keeping your gaskets from leaking. This happended to me twice before with older MBs, so I do not change TO synthetic. I have never had much luck with the "Stop Oil Leak" products that try to expand the gaskets, or try to block the leaks.

Check your ambient Temp guide in the MB manual for proper oil weights for SF.

Good Luck.