I will kick this off: I have been using Liqui-Moly 5w-40 but on my last oil change I went to Mobil 1 5w-30. I had the Liqui-Moly analyzed by BlackStone-Labs and it came back with good results, however Mobil 1 was much more readily available so I went with that.

Both oils seem very similar in use: on a hot day in traffic both gave 1 bar at idle and 3 bars at > 1,000rpm.

 

Castrol the syntek version 5-20 ?? only drive 5K at most each year.
On several Benz models
the super thin Mobil 1 has not been a good change. too many spots of oil on the garage floor!

 

5W-40 Castrol Edge full synthetic (formerly called Syntec)

 

This car has always had mobil 1.

When I got it three years ago I was using 10?40. Now I'm buying qt cases at the dealer that are officially Mercedes Benz oil but I was told they're really mobil 1. It's 5-40.

I think you want to make sure it passes Mercedes 229 specification. Not all mobile 1 formulations are the same.

Edit: I would add my experience with Mobil 1 over 40 years. It's pretty amazing stuff. Had a car run out of coolant - engine got hot enough to crack both the cast iron block and aluminum cylinder head, and we still used the cams and crank into the new engine. Of course that protection is more academic when your engine is ruined anyway.

I have noticed with our high heat in summer - 40C or over 100F - it will idle at .5 bar. Or less.

Here's a picture of the valve train when I had to replace the oiler tubes.

 

oil

Last two times I have used Duratec semi-synthetic 10/40, I can buy 20 litres for just under £40(trade price) 3 bar pressure all the time apart from idle when it goes to 2 plus.:smile

 

I voted Valvoline, but I didn't read that you were only looking at synthetics. I am using Valvoline VR-1 Racing Oil 10w-30 in the dino version and absolutely love it. Just by using the gauges as a barometer the car runs slightly cooler with it but holds great pressure. They also have a full synthetic version. I recommend you look into it. I buy mine at the local Napa Auto Parts.

 

This stuff. $7.63 a quart.

 

But do you know where it is made?
I've been fan of Castroll for decades and Walmart has good price on it.
BTW engine with perfectly clean internal parts indicate to run more on detergents than on oil. New oils have overdose of detergents and if changed too soon- they do that.

 

For me the choice is mainly about maintaining a 'good' oil pressure at hot idle when ambient temps are up around 30 to 40deg C. (Summer driving hols in S France over Alps :grin). A gradual drop in the hot idle pressure would indicate to me that the viscosity modifiers (long chain polymers) in the oil are starting to break down.

I buy top end fully synthetics so I take the lubricating properties for granted, but I favour the higher zinc content formulations.

I experimented with several makes and weights within MBs spec and found that mid range Casfrol or Mobil 10w/40 5w/40 0w/40 synthetics hot idled at 1.5 to 2 bar when new, but thinned out quickly after a longish hot run and hot idled permanently thereafter at 1 to 1.5 bar.

For years now I have used race derived tri-ester fully synthetics. My favourite is Millers 10w/60 tri-ester, then Mobil 10w/60. Hot idle never drops below 2 bar and I do mean never.

Happy Days!

 

Engine oil

Hi, in response to the question of which type or brand to use I had a conversation with my friend who is a race car engine builder on the side. He is also a machinist ( he is fabricating my head rest gears). Over a couple of beers we started talking about this same topic. His wife owns MBs and he does the work on them. He asked what kind of oil I used and I said synthetic. He told me that a 1991 motor ( even a MB one) was not designed for synthetic oil. The tolerances in a motor of that design would not be as effective using it. He believes at high temp the oil would be thinned out and not providing proper lubrication. H noted that is his opinion and one that of course can be challenged. He used the new Dodge Hellcat motor as a example of a motor made to almost unbelievable tolerances to get crazy hosepower and made for only synthetic oil. As in MB the oil pan is large to make sure that under hard use you do not have your oil pick up starved and also to assist in cooling. Then our conversation switched to suspension and I got completely lost so I drank lots of beer and just listened.

 

Hi Roscoe,

I use Mobil 1 Full Synthetic HIGH MILEAGE.... it was what the MB Dealer recommended for my SL500 M119 engine.

It is available in 4 viscosity grades..... 5W20, 5W30, 10W30, and 10W40.

See attached for a summary.

God Bless, Arctic

 

One thing that has amazed me (in a pleasant way) about my engine is how little oil it consumes. When you buy a (then) 17 year old car that is a cause for concern. And most of that seems to be leakage somewhere on the right side (I got ample opportunity to see it while wrestling with the motor mounts a month ago).

I doubt that I use a quart in 7500 miles. Car has 165,000 miles. According to a dealer tech who has gone on our club drives, this is not unusual for the M119.

The "Mercedes-Benz" oil someone else showed (I use it now too) is Mobil 1 5w-40, according to my parts friends. That must be a viscosity strictly for Mercedes as I have not seen it in the US in a Mobil 1 container.

 

One thing that has amazed me (in a pleasant way) about my engine is how little oil it consumes.

Agree totally. My M119 has 105,000 miles on it and it consumes virtually none, I never have to add any oil between changes. Superb engineering has to be the reason.

 

Royal Purple

I note that 2 poll respondents are using Royal Purple oil - could they tell me which type (HMX, HPS, etc)? and what viscosity? Thanks in advance.