My 91 300SE has 116K miles on it. I'm female, I don't know a whole lot about cars, but I can change my oil and air filter, fuses, minor type things. I want to be a little independent when it comes to my cars. For my oil changes, I went to Kragen about 3 years ago, and they have me using Max Life 5W 30 Synthetic Blend, which I have not had any issues with. I found an old oil container in my trunk and it seems like I previously used 20W 50, which I believe it what the manual says to use. I could not find a section on this forum for oil info. Do any of you DIY guys have any preferences on what you use for oil? In my 93 Miata I'm using Max Life 10W 30 Synthetic Blend. That car has about 170K miles on it. No issues with that car either. Any advice would be appreciated!!

I dont think you need synthetic oil, I would use Rotella 15w 40 its a diesel oil but is good for the m103. Regular dino oil is good enough, synthetic is a waist of money if you do regular oil changes.

exactly this. Stay away from synthetic in your car, it will cause more problems than it will solve.

Rotella 15/40 only, and if it's cold where you are at 10/40 or even 10/30 in winter.

rjp

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03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)

I'm sorry but that is just bad advice. There is absolutely nothing wrong with running synthetic oil. With that being said, Rotella or Chevron Delo 15W-40 are both excellent oils for their higher ZDDP content. Changing your oil on time and using a quality oil filter are more important than choosing one brand or grade of oil over another.

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1989 300CE

1)- being a 1991 the car wasn't designed with synthetic in mind. Oil has changed and not for the better:

See report by Charles Navarro of LN Engineering: Oils: What motor oil should I use? Which oil is best for my Porsche or aircooled engine?

2)- Synthetic oil has low ZDDP.

3)- it is proven to cause leaks, or hasten the onset of leaks.

4)- why screw with something that works fine?

5- it's a big waste of money, doubles the cost of the oil change and high risk for what? No benefit in this case (unless you count leakage)- a 116K motor that's 20 years old that at best, has questionable seals? That's all you will get.

Don't believe the synthetic hype. You, or the car will not notice the difference. It's marketing BS.

rjp

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03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)

1991 300SE Owne, as you can see everyone has an opinion on the oil and oil viscosity that is best for your engine. If you do a "Search" using "Oil" or "Oil Changes" you will find many threads discussing the subject ... hours worth of reading.

The factory fill for that vintage engine was 15W40 mineral oil. Check the index in the back of your Owner's Manual under "Fuels, Coolants, Lubricants, etc." for the page with a chart that- shows oil grades (weights) versus ambient temperature.

Synthetic oils have swell agents that prevent gaskets/seals from leaking. Since you have been running synthetic oil in your 1991 300SE without any problems it's fine to continue using synthetic oil in my opinion. I use Mobil 1 15W50 in our engines of that vintage and have never had any leakage issues, even when switching to synthetic oil after 100,000 miles. The Service Booklet recommends oil changes every 7,500 miles and I follow that frequency religiously. (I also use Mobil 1 15W50 in my John Deere tractor engine. During a recent camshaft replacement at 1,065 hours, a known Kawasaki engine issue, the service manager said the original cross hatching on the cylinder walls was visible. Meaning the engine showed no/little wear.)

Bottom line: I would continue with synthetic oil. George Murphy, the Technical Director of the Mercedes Benz Club of America, endorsed Mobil 1 during a tech session I attended in 1998 so I have been using it since then. Our local MB dealers use Mobil 1 for all oil changes.

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Fred Hoelzle

Theres a few Mercedes engineers out there that would beg to differed. I switched my m103 to synthetic rotella 5w40 at 150k miles when I bought it. No problems 3 years 37k miles later. I change it once a year regardless of the mileage. If synthetic oil is going to kill my engine it better do it soon before I get bored with it.

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CENSORED due to not family friendly words

Deanyel, I am in Northern CA, Sacramento area. I can't find my manual at the moment, and after I found the old bottles of 20W 50 in my trunk, I decided to do the post. I used the 20W 50 when I lived in Los Angeles. I'm not sure now that Kragen's advice of 5W 30 is the best? I do change my oil every 7,500 miles, probably earlier than that. I used to change it every 3,000 like I do with my Miata.

It's my understanding that by using the synthetic 'blend' I could go back to regular oil if I wanted to. That is why I was using the 'blend'.

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

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03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)

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 -

Attached Files

Oil Viscosity.pdf (21.6 KB, 163 views)

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.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

Are you running it to the same change intervals?

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Jim

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

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

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