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What Oil Viscosity are you running and why?

5K views 25 replies 16 participants last post by  Pete S 
#1 ·
During my most recent trip to the dealer (actually it's there now, and I'm tooling around in an '08 C300 Sport with 500 miles on it...nice little car), they told me I should be running 0W-40 or 0W-50 in my car because it is considered "high-performance". I was like Huh?

But anyway, I said "but this is Florida...it's 100 degrees out...you really think that's necessary?". I would have just dismissed this outright, but it was actually a tech talking to me and not the SA, so it made me think twice about my belief that thicker oil is always better, even at the low temp end, unless you live in Alaska or something...

So I pose these questions to you all:

What oil viscosity are you running, and why?

Have you noticed any changes when running different viscosities?

Also, for those of you who have fallen off the Mobil1 wagon (which I think I am about to do, if I can find a US dealer for Penrite, or I have heard good things about RoyalPurple), what are you running and how happy are you?

TIA

-Chris
 
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#3 ·
I live in Pa. and I use Mobil 1 0-40
The reason being it is what mercedes recomnends
They should know they build the engine
besides oil is so good now its not going to make it better by switching if you use a good brand.
I worked in industry for over 30 years and also raced cars and the only way
I seen failures due to oil was the lack of oil or never being changed!!!
just my 2 cents
 
#4 ·
Chris, The topic of oil is as volitile a subject as there is!!! I will answer your question as best I can. I run 10-30 Mobil 1, only drive during the summer, 60-95 degrees, Oil is a very personal thing!!! It does a good job for me. Royal purple is a good product, I first heard about it at the track 10 or so years ago. As far as I know its a little hard to find. M-1 can be found anywhere. I guess I would sum it up by saying, It has always worked fine for me, and I will continue to use it. How would someone know if their oil was not working???? {before its to late}???
 
#5 ·
Viscosity is easy to work out from your own geographical location, however oil quality is another matter.

aam will appreciate this axiom "Oil's cheap, engines ain't".
Never ever try to save a few pennies by buying cheap oil, those saved pennies will cost you thousands when you have to pay for major repairs to your engine.

I still find that Mobil 1 synthetic oil is the best that money can buy. When I first used this oil in a single cylinder Lister generator I could not believe that after hundreds of hours of use when I did the routine strip-down service, I could still see the original honing marks on the cylinder bore. Another testimony is when I poured a little on to an oil stone to sharpen a wood chisel, I couldn't get a proper metal to stone contact (try it).

The winter temperature here doesn't usually drop below 12ºC, and in summertime it can go over 40ºC so my Mobil 1 5W-50W covers every eventuality :thumbsup:
 
#6 ·
I hear you RedLiner.
I am running on 20W50
I would be very careful with big space oils, they have more additives in them.
The question one has to ask is, can you run on additives only?

It is in my nature to side track so I will not brake my tradition.

Some time a go doctors and of course manufacturers were saying that it is better to give
there formula milk to the babies, so most mothers were feeding formula to the poor babies.
Now with many studies after they found that the best milk is the original, better yet if he/she drinks it from the top.

This morning was in the news, babies who drink mothers milk are more intelligent.Ehehe.

Ok , ok I know we are talking about cars.

The engine needs oil......and some additives.
0W50 look at the space it has a lot of additives.

I am in California my car will never see cold.
And it is good from 0 degrees F to all the way up to hell.

Synthetic oil in an older engine, maybe yes, maybe no.

On this RL don't get me wrong, not in my engine.

Replace your oil more often your engine will thank you.
Synthetic or not.

I will say it one more time, sometimes I will replace the oil at 700 miles but not the filter.
Because of the time limit.

Remember it is always better to feed your baby from the tit.

No formula thanks.
No synthetic oil for my baby.

Regards.
aam.
 
#10 ·
I have used the 15W40
The new one is for all engines Gas and Diesels but I am a little skeptical.
I know they lowered the chemicals in it, but they can damage the catalytic converter in the long run.

So I don't want to take the gamble.

LOL.

I didn't forget.
Oh yes, about the TTs are trouble.
But a nice one.

Regards.
aam.
 
#11 ·
I am up in Canada, only run the SL in the summer time. I have an Indy who was a mechanic at the local dealership, worked his way up to service manager and then retired to his own shop, working at his own pace. I am a Mobil 1 fan and told him I would bring in my own oil, but he nearly flipped when I suggested anything other than a 15w-50 in Mobil 1. He said the other lower viscosity oils in the Mobil 1 line do not meet the high temperature sheer specifications that Mercedes requires. He would have prefered that I run Amsoil, but I ended up sticking with my Mobil 1. I did find a couple articles backing up what he had been saying.
 
#16 ·
...the other lower viscosity oils in the Mobil 1 line do not meet the high temperature sheer specifications that Mercedes requires...
I completely agree. And this is not just for the high performance Mercs. My old trusty 190D 2.5 diesel really gives oil a hard time when it gets warmed up too.

There is a simple objective test to prove your point. Fill your baby up with a cheap lower viscosity oil. Something around 0w-40 0w-30 and run it for a week or two, going for a short gentle drives, warming the engine up to around 85 deg C. Check the oil pressure at idle, which will probably be around 2 bar. Then go for a long(ish) hard blast down the freeway (200+ miles). Drive around again gently to let the oil temperature settle back down to normal operating (~85 deg C). Park up and check oil pressure at idle again. All of a sudden it will probably be quite a bit lower than 2 bar because (assuming its not dilution from overfuelling) the stress from the long drive has sheared some of the long chain oil molecules and made the oil thinner i.e. less viscous. You don't want this. This is bad.

Albert made a very good point about the space in the oil. Oil companies use polymer additives to extend the range of the oil (in case of 0w-40 the range is 40, 0w-30 range is 30 and so on), and 0w-40 oils have been known to be the worst for problems caused by the overuse of additives, resulting in shortened oil life, and in some cases excessive engine wear and sticking piston rings.

With Mobil 15w-50, 10w-50 and 10w-60 you shouldn't get a noticeable drop off in viscosity idle oil pressure over time.

Give the test a try. I let you decide.
 
#12 ·
Well they already had completed the oil change by the time I got ahold of them on Friday, so I guess I will have to live with 0W-50 (IIRC) or whatever it was for awhile. In 3000 miles I will probably switch to Amsoil or Royal Purple.

And aam is correct. Mobil1 just screwed up their own product line, trying to comply with an EPA suggestion, except for like two viscosities...IIRC 5W-50 and 15W-50. Those are the only two with the original sulphur contents remaining. Sulphur is an excellent lubricant, but can have adverse affects on a catalytic converter, so our wonderful government decided that it's a great idea to protect a sub-$1k part of the car at the expense of a $20k part of the car: The engine. So they lowered the max sulphur content allowed for general-use vehicles by a large margin. Makes sense to me...not.

Anyway, the Porsche guys have figured out that GM makes an engine assembly lube called EOS, which mixes well with Mobil1 and is basically all-sulphur. So they put a quart of that in along with their regular Mobil1 to replace the lost sulphur. There was a huge discussion about it on MBWorld awhile ago.

So anyway, I will see if I notice any sound differences from the 0W on startup.
 
#13 ·
15w-40 is a great choice in hot climates. 50 weight is too thick even for the hottest weather, it'll just bog down the engine. HD oil like Rotella comes in a thick 10w-30 too, I would do a gallon of each.

A good 10w-40 High Miles like Pennzoil is also an excellent choice out to 6000 miles. Mix it down with 30 weight to flavor, I'm doing about half and half.

Two short changes is better than one long change. There's no substitute for physically draining out contaminates, excess fuel, condensed water and oil oil mixed and warmed, yuk.
 
#17 ·
I have been using Mercedes USA own oil, which is synthetic 5w-40. Was told it was made for them by Mobil 1. Have used Mobil 1 for years. Synthetic oils hold up far better with lower viscosity than conventional oils.

When I got the car I could hear a lifter ticking - now driving it regularly with my oil has eliminated the ticking.
 
#20 · (Edited)

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#21 ·
Hi Richard, I believe the relevant datasheet for R129 engines 103.985, 104 and 119 is MB 229.1, which is compatible with the wider range of SAE classes shown in your handbook / owner's manual. See the following link: -

MB 229.1 - Multigrade engine oils (Specification 229.1) - Mercedes-Benz Specifications for Operating Fluids

Petronas 3000E 5w40 fully synthetic is not shown on MB 229.1. Presumably its a more recent oil meant for the newer range of MB engines that suit datasheet MB 229.5.

The Mobil 1 10w60 that I use meets 229.1. Here is the link to the Mobil spec sheet: -

Mobil 1 Extended Life 10W-60 *

Features and Potential Benefits

Mobil 1 Extended Life 10W-60 is engineered to help provide long lasting protection in higher mileage engines so you can get long life out of your vehicle.

Extra seal conditioners to help prevent oil leaks
Helps to reduce sludge build up to keep engines clean and prevent wear
Outstanding/Excellent oil film thickness for extra protection in older engines
Higher viscosity to help reduce oil burn off in older engines
More anti-wear additives to help protect worn engines
High performance basestocks for excellent all-round wear protection

Applications

Mobil 1 Extended Life 10W-60 has been designed to help provide the extra protection that older engines can demand. It is suitable for virtually all types of older vehicles and operating conditions.

Older vehicles
Nearly all operating conditions, from mild to extreme
An ideal product for Racing applications

Always consult your owner’s manual to check recommended viscosity grade and specifications for your particular vehicle.

Specifications and Approvals

Mobil 1 Extended Life 10W-60 meets or exceeds the requirements of:
API SN/SM/SL
ACEA A3/B3, A3/B4

Mobil 1 Extended Life 10W-60 has the following builder approvals:
VW 501 01 / 505 00
MB-Approval 229.1
 
#22 ·
AIUI the engines should use MB 229.1 or better (229.5 didn't exist back in the day) 229.3 hits and exceeds 229.1 std and 229.5 hits and exceeds both 229.1 and 229.3 standards

Opie oilman has discussed this on MB UK, apparently 229.1 is quite an easy std to hit 229.3 a bit harder (budget stuff like triple QX)
229.5 current latest standard.



Not saying your right or wrong.
 
#23 ·
Although Datasheet 229.5 is supposed to be backwards compatible, MB229.1 was updated to MB 229.3 as a result of the extended service interval coverage required on more modern FSS engines of the line. Not sure what the reason was for the update from MB229.3 to 229.5.

For me the question is: - In an older engine from the early 90's where the bearing tolerances are higher as a result of age of manufacture and wear, do I trust the lighter based ester formulations of MB229.5? My answer is no. I have tried MB 229.5 spec oils. The viscosity of the oil was more like water, which made me initially uncomfortable putting it in an older engine. And when the engine sounded louder and a bit more clickety clackety, I changed back.

For my older M119 (originally designed as a non-FSS engine) I believe that MB 229.1 is more relevant. But there are people would would disagree and use the MB229.5 spec regardless.

On a similar note, my MB dealer now only sells SAE 75-85 differential oil. They said this is backwards compatible to the original spec. Tthe original for my 1991 500SL (non LSD) is SAE 85-90, which is noticeably thicker. Since using the newer oil I have noticed a slight leak from both diff seals. Or it could be frothing and coming out of the vent tube. (I haven't overfilled it). I think I will be sourcing an alternative diff oil.
 
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