Oil Question: NOT Brand .... weights ......
 

I have three cars: 190E 2.3, 300E and a 95 E320. I'm confused about weights for the summer driving season. I've seen where a 10W-30 is fine (and helps with fuel economy) and I've also read where in the summer in N. California, the minimum weight should be a 10W-40.

I know ..... here we go ....

Haasman

The so called *economy* viscosities are a farce. They are recommended by car manufacturer's so they can report a few tenths better mileage to the government to help their Corporate Average Fuel Economy numbers. You won't notice any difference in economy but you will be compromising long term reliability.

If you own a Mercedes, follow the recommendations in your owner's manual. Mercedes are still more interested in reliability than in avoiding gas guzzler taxes (can't say the same for US and Japanese manufacturer's).

I wouldn't use anything less than 10W-40 in northern California (summer or winter).

I like to go with MB's latest recommendation: 15 W 50.;)

Thanks for the replies .... you are confirming what I believed were the correct viscosities.

Haasman

Your owner's manuals show the recommended viscosities for the temperature range you expect to see prior to the next oil change.

My '88 owner's manual shows 20W-50 as suitable for all temperatures from 32F to the highest expected, which should be suitable year round in Saratoga. Interestingly 10W-30 is only listed as suitable for temperatures from -4F to 50 degrees.
My manual shows 10W-40 as suitable from -4 to the highest expected, but GM, in particular, does not like 10W-40s because they have the highest concentration of viscosity index improvers, whose oxidation products they claim increases combustion chamber deposits.

These recommendations are specific to mineral based oils. Synthetic oils have a broader VI without the addition of VI improvers or with very little VI improver.

Duke

You will not find any European car that recomends xxW-30. From what I have seen and read ALL European cars take xxW-40 or higher. For conventional oil I would use 10W-40 or 15W-40. For synthetic 15W-50.

The oil in my car was changed by the dealer from new until 127,500 miles, and the oil they used everytime was Castrol 20W-50.

My 560SL (145k) shows the same manual recommendations as mentioned above; 10W-30 for temps to 50F only, 20W-50 for temps always above 32F. Somehow at the last oil change a couple of weeks ago, 10W-30 was put in, and I since noted a light bit of blue smoke on starting off from rest after idling, more with prolonged idling and when hot, as well as consumption of a quart per 300-400 miles. No later than this weekend, I'll get the light stuff out of there and 20W-50 put in; I expect to see it improve.
I can think of no reason not to follow the manual on this!

Here in Massachusetts I run 10w-40 in the winter months, and 20w-50 when its warm. The theory as to when to change is simple: If the month has an 'r' in it, it's cold. :D

what about for 15 to 40 degrees celsius what wight would be ideal for my 16v

So exactly how bad is 20w-50...
 

in temps as low as 10F? I live in NW Arkansas, and that is as cold as it gets, usually hovering from 20-40 daytime lows-highs in Dec-Early Feb.

Am I killing this engine (and all the others I do that to) by doing that? I always give 5-10 min to warm the engine.

Also, I just noticed that I have a block heater. Would that help in cold conditions (ie not harm it with running 20w-50)?

Thanks for any help.

MY 50,000 mile '96 C36 AMG just got another fill of 10/30 mobil one here in hot Houston. My car is ALOT quieter w/ the fresh oil on start up. It was rattling for about 5 seconds on power up w/ the 6,500 mile oil in it? I am guessing that the oil is loosing its polymer qualities based on the sounds going away w/ the fresh oil?? Should I run the 15/50 also?? I might go ahead & goto the thicker Mobil one stuff like SOON?? My car was starting to sound like the Diesel that the motor is based on!

08/09/03
I have watched this post grow to 5 pages so far & I am now running 15/50 Mobile One this time around and probably for now on. It gets up to 105deg here in Houston & I know the 'hot' turbo cars usually run 15/50. t rarely freezes in Houston.

Amazing the opinions about this subject??
Kinda like religion, everybody has thier own faith, takes it extremely seriously & nobody really knows the truth!!!!!

I use 20w/50 year round...
 

If it won't start, it's too cold for 20w/50.. That's my rule..THere is no doubt in my little mind that it lubricates better than a thinner oil, and provides a better cushion..

But cold weather does become an issuse.. Especially if it won't start:D

moparmike

It is my understanding that "giving the engine 5-10 minutes to warm up" is not a good idea. You should let it run for 30 seconds max and then drive off. Once temperature appears on your temp gauge then drive normally.

An idling engine does not warm the same way as an engine that has some RPM and load does.

Haasman

You should follow the manufacturer's recommendation for oil viscosity (as listed in all owner's manuals) based on the range of ambient temperatures the car will see until the next oil change. It's that simple, and the low end of the 20W-50 range is usually no lower than 20F, which would not be suitable for most climates in the interior US during the winter. My '88 MBZ owners manual lists 32F as the lowest for 20W-50.

On a cold start the car should be driven away as soon as the idle stabilizes, which is usually a matter of seconds, but you should use low revs and light throttle until the temperature comes up to near normal. (Note: Some MBZ models are designed to hold lower gears longer when cold to speed warmup. I'm not sure if I like this philosophy, but that's what they did.) The worst thing you can do is get right on a freeway and have to accelerate to speed with a cold engine. If you live next to a freeway ramp, use surface streets to drive down to the next on-ramp so the engine has a chance to warm up. Low to moderate speed driving also allows the transmission and axle to warm up along with the engine.

Modern engines are designed to warm up quickly, and low to moderate speed driving will usually get them up close to operating temp in under five minutes in mild to warm weather. Since most engine wear over the life of a typical automobile engine occurs during cold start and warmup, it's best to get the engine warmed up quickly, and this is best accomplished by driving the car at low to moderate speed immediately after a cold start.

The other thing to remember is that the oil takes longer to come up to operating temp than the coolant, so I avoid WOT high rev acceleration until at least five minutes after the car comes up to full coolant temperature.

Duke