Just did an oil and filter change in a 94 E420. Put in 10W40. Car used to have 20W50. Is the 10W40 going to do anything bad?

yeah I know, too late as I am asking this after the fact, but in any case, do you think I am going to have problems?

I really don't think you'll have problems. Rarely do I hear of anybody who changes their oil regularly cause damage to an engine because of their choice of oil. This is, of course, excepting extreme situations such as using 0W-20 in Australia's summer or 20W-50 in Saskatchewan's winter.

10W-40 dino grade has lost popularity for many people. It used to be the oil of choice two or three decades ago, but not anymore. To push the 10W oil so it would thicken at elevated temperatures, more viscosity modifiers are added to the formulation when compared with the 10W-30 grades. These additives are more prone to leave sludge and deposits in an engine.

In Atlanta's summer, my choice would be 15W-40, 20W50, or 10W-30, in that order, depending on the type of driving you do.... short trips or extended highway driving.

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95 E320 Cabriolet, 159K

Basically you're going to get one of two answers: YES it will; NO it won't.

Now which do you believe?

I would only be concerned if the NO answer came from one of the members here like Jackd or someone with some legitimate industry credentials.

I bought an Isuzu Rodeo new in 1995 and got a copy of the factory service manual while I was at it. Page 8 said that using 10W-40 could shorten engine life. I wrote 2 letters to Isuzu about it. Never got an answer.

I then wrote letters to Pennzoil, Quaker State, Valvoline; Castrol. Pennzoil and Castrol responded and the short answer was NO. I could safely use their 10W-40 in my Rodeo.

That was 10 yrs. and 200,000 miles ago and the engines life has not been shorten by the use of 10W-40.

Is a '95 Rodeo the same as an MB? No it's not, so on the end, you're simply going to have to do some research and form your own opinion, but I would base it on what you hear from industry officials and not what you read here from all the oil wanna-bees.

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'91 300-SEL

AtlBenz, the local MB dealer fill for 1994 cars here in PA was Quaker State 15W40 mineral oil. Since you're in a warmer climate probably better to use a multi-viscosity oil of 15 weight minimum in the future.

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Fred Hoelzle

I live 2 hours up the road in Greenville, SC

I use 20w-50 from March-November... then switch over to 10w-40 in the "WINTER".

300E 151K MILES. burns no oil in between 3k oil changes

thanks guys.

Yeah I was expecting either:
1) "OH MY GOD YOU FOOL! YOU ARE DOOOMED!"
2) "Naw, its okay, you'll be fine."
or
3) "I did the same thing last year and had 7 out of the 8 pistons rip through the hood."

I see now that it’s probably not something to worry about, especially since I do frequent oil changes. But for the next oil change move back up to the 15W or 20W's like you guys have suggested. Do you think I'd have to change the filter again since I’ll be using different oils?

I am still a bit hazy on the viscosity numbers. As I understand it, by using 10W40 (as opposed to 20W50) I've moved to an oil that thinner at both low and high temps; which isn’t bad per say, but its also not optimal. I guess for these M119s, 15 is the minimum thinness one should go. And at the high temps one wants thicker oil right correct? Which would mean a W50. Sorry guys, just thinking out loud.

To answer your question about needing a 50 weight on top...

It is highly unlikely that your engine could be hard enough on any of the HDEO 15W-40 oils such as Delvac 1300, Delo 400, or Rotella to even put a dent in them when it comes to higher temps.

These oils are a step above the average 10W-40 in the quality of their base stocks.

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(2) 1988 300 SEL W126

Here's the opinion of someone who knows a thing or two about oil.
My opinion is: well.............
After having read about 10,000+ oil posts on different car forums, I still have to read one post (only one) where it was clearly demontrated that the use of any oil (from high priced synthetics to cheap Walmart no-name) has been the cause of a mechanical failure or premature engine wear.

The gentleman who started this tread has a 11 year old car with god-knowns what oil has been used over the years. Do you really think a single oil change with a different grade of oil will result in something bad?
If the oil used is within the engine manufacturer's recommendations in terms of grade and changed as required, a modern engine will last until your get tired of the car....and more. That includes synthetics, dino, and even a good grade of recycled oil.

AtlBenz

Sorry, can't help you........after getting criticized, chastized, terrorized & circumsized on the last oil thread.

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2007 C 230 Sport.

not really, but I was just making sure.