OK, Someone's Lying. . .

[bobs]

Stopped by the dealer yesterday to get some oil & a filter for my newly purchased '97 S420. He says that the recommended oil is 15W-40 non synthetic. Two weeks a go I went to another dealer to get a filter foy my '97 S320 and they told me that the recommended oil is 0W-40 Mobil-1. So, who's telling the truth?

All the car's maintenance records show that the previous owner took it to an independent shop who always filled it with Castrol 5W-40. So now I'm really confused.

I'd like to switch the car over to Mobil-1, but is that advisable on an engine that has 85k miles and a couple of weepy gaskets? I'd appreciate any thoughts you could share.

[Peter Guenther]

Synthetic oils are claimed to have a longer life, and lubricate better. That is why they are not suggested for engines with weapy gaskets. My service advisor switched me over on my (92 500) and I have no issues, and change it at near suggested intervals 8/9 Kor at least once a year. It has 94K and have been doing it for the last four years. Since most new cars are using synth the dealeships are encouraging it, they are getting it in bulk, and one less chance to put in the wrong stuff.
You can continue use dino oil, and that is probably what your car was delivered with and the previous owner continued doing so.

[t walgamuth]

15w40 non synthetic is most likely diesel rated oil.

I think he looked on the wrong line in his book.

That gasser engine should be getting the lighter oils, probably the PO was using what is needed, but you need to look in your owner's manual to see exactly what.

Tom W

[mbdoc]

In the automotive business you found some one lying???!!

Doubt any one was lying....BUT would think they were giving their opinion!

MB suggested that regular "dino" oils are the recommended type for that year car.

When they went to FSS system & oil changes are extended to 10K+ miles they recommend synthetics. AND since they a contract with MOBIL oil company, they recommend their OILs.

However 99% of the cars that leave the factories have FUCHS brand oils in the drive train components.

I wouldn't advise a using a 15W-40 oil that far north.

[Maxbumpo]

Bob,

If you've already got some weepy gaskets, standby for increased leaking if you switch to the M1. At least, that is the common wisdom. In my experience with two high mileage MB diesel engines, the minor leaks actually improved when I switch to M1.

[Ferdman]

Bob, check the recommended oil viscosity vs. ambient temperature chart in the Owner's Manual. I run Mobil 1 15W50 in our cars of that vintage with no problems. Mobil 1 has swell additives that help prevent against gasket leakage ... never had any leakage problems when switching from conventional oil to Mobil 1 on 124 cars with over 100,000 miles.

[bobs]

Thanks for all the advice. I'm really partial to M-1 so that is what I would prefer to stick with. I ran 0W-40 in my M112-engined Crossfire, and my M104-engined S320 seems to be happy with it (good pressure, no lifter noise, etc) as well. So is there any reason I wouldn't want to run it in the M119?

No reason at all. 0W-40 M1 will be just fine.

[manny]

Originally Posted by mrhills0146

No reason at all. 0W-40 M1 will be just fine.

Exactly what I would use as well.

[Texholdem]

I have Mobil Oil 10W-40 and 0W-40 one gallon each and my car needs ~8 quarts.

Is it a bad idea to mix oil of different grades, same brand? Would the mixture result in 5W-40?

[Dee8go]

Oh, half and half. I don't think I've ever heard that before except in coffee.

[lee polowczuk]

i've done it before..

[t walgamuth]

I do it routinely. I know others who do too.

Tom W

[TheEngineer]

I sometimes put Baileys Irish Cream in my coffee. In my '95 E320 I run Mobil Delvac 1300 Super 15W-40. It's advertised to be a 100,000 mile oil. Good stuff!

[Texholdem]

In order to use up my stocked oil I gonna buy two other gallons, one 10W-40 and one 0W-40 for the next 2 oil changes, each time only one grade, no mix.

Do you find it then OK Dee8go?