the biggest issue is that the older oil formulations (when your car was new) had ZDDP- an anti wear additive.

They started eliminating that additive around the late 90's, reason is that it when burned it causes Catalytic converters to die. However, in some engines it has caused the camshafts to go flat.

using certain formulations (like Rotella diesel- what I use) has higher concentrations of ZDDP- the latest "standard" passenger car oils all are formulated basically without the stuff.

rjp

I have been happy with this oil in any gas engine i have used it in Lubro-Moly- MoS2 Antifriction Motor oil 10W-40 (this is not a link to anything in competition with products sold by this site), it is available from napa auto parts for $35 for 5 liters. When I used it in the milano I used to have it made the engine noticably quieter and increased hot oil pressure over 15w-40 rotella or royal purple oil which i had used before.

As Gilly says you'd be fine year round with 10w40, or 15w40 would be fine too. The oil viscosity chart with your owner's manual probably looked something like this -

I purchased my 1988 260E from Von Housen Motors in Sacramento. It was delivered with 15W-50 Mobil1 and always filled with the same at every service there. The temperature range/viscosity table in the owner's manual suggests that that's the right viscosity oil for your climate. I have long since changed from synthetic oil to Castrol GTX with no ill effects at all.

Are you running it to the same change intervals?

I also run 15w40 in my M104.Diesel oil is just better I change mine every 3500miles.

Every 3500? You should get the oil checked, you could probably stretch that out to 7500 without worry.

-J

Naw oil is cheaper than metal.

1988 Mercedes were not delivered with Mobil 1. Somebody is telling you stories.

Ya and changing it 2x as often as needed accomplishes nothing except using more oil and actually increases engine wear slightly.

Spend the $20 and have it checked.

-J

Sny oil.
 

Go with the owners manual recommendations. DO NOT switch to pure syn oil on an old engine unless you are prepared to change your oil every 1500 miles for the first year. Syn oil will super clean an engine that was using dino oil. It in itself doesn't cause seals to leak. It simply cleans away all the sludge that was helping to seal the worn seals. Syn oils bennefits are: No sludge. No varnish. And, your engine will never get hot enough to burn syn oil. Thus no sludge, no varnish. I don't know what the ratio is in the "blend" you're using but, it's probably about 10 percent. And that should be okay. Syn oil was recommended in 'vettes from '92 on. Not because they are special engines, but because they could delete the oil cooler and save a little weight. Again, syn oil won't burn or vaporize. (Unless you're about ready to chuck a rod). I've torn many 150k engines down and a blind man can tell if it was usning dino oil. You could make a Christmas candle out of the waxy sludge that comes out of them. A syn oil engine with that milage looks like it was put together the day before.
Now, unless you're planning on buying a brand new car and keeping it for twenty plus years, and it's not a late model 'vette, go with dino.
MTCW Good luck.

No stories Dean. I'm the original owner, I have all the maintenance service records as well as the dealer's initial vehicle inspection report. Mobil1 15W-50 was in the crankcase from day 1 until I changed to dino oil in 1997.

How do these myths get started? Over the years I switched 7 cars to synthetic at over 100k miles when we bought them (M102, M103, BMW M42, Volvo B6304, B230f, B5254, B4204t) and none of them developed any problem or leaks. I change the oil once a year. Synthetic rotella 5w40 hdeo in everything.

Lucky you. No need to spend the extra $$$ however. There is no tangible benefit on these cars.

On newer cars, do what the owner's manual says.

rjp

I use synthetic oil because its cheaper than non synthetic. I change the oil once a year at 8000-15000 miles intervals.