The Best Oil in Hot Weather... - PeachParts Mercedes-Benz Forum

jassz · #1 08-03-2003, 10:20 AM

We are planning to do an oil change in preparation for our road trip east next week. I picked up the usual 15W40 oil (Rotella), but my husband wonders if we should be using a thicker oil since we're going to hotter country. It rarely gets over 30C here(I can't remember the conversion but I think that's about 85), but where we are going could be over that.

So... he asked me to ask that question. I replied, "You want me to ask an OIL question on the board? You don't know what you're asking! It's too controversial, it's better to stick to world politics!"

But, there you have it. Question asked. Don't shoot the messanger.

#2 08-03-2003, 10:46 AM

Rotella 15w40 is just fine. Use it without worry.

84300DT · #3 08-03-2003, 11:10 AM

i second that emotion...
15-40 year round here from below freezing to 30 deg C and higher.

jassz · #4 08-03-2003, 11:17 AM

Okay, I guess I didn't get the question quite right.

The question is, would a thicker oil smoke less? Ever since we added the hydraulic fluid, which I think went in to the crankcase, it has been smoking more. It seems too thin, so maybe it's leaking past the valve seals a little easier?? If that seems logical, then it seems logical that thicker oil would smoke less...?

True?

84300DT · #5 08-03-2003, 11:31 AM

just a question, why would you put hydraulic fluid into the engine
crankcase?

i would guess that 15-40 engine oil would not make you car smoke more or less than any other grade.

leathermang · #6 08-03-2003, 11:32 AM

Why do you think Hydraulic fluid went into your oil ? If it did you need to change it out immediately. and you should have when you thought that happened in the first place... a diesel does not need the oil diluted with anything like hyd fluid.... or diluted period... too much stress on the bearings....
Smoking is usally due to bad fuel usage.. either timing,injectors,clogged precombustion chambers, or mis adjusted injection pump..... or leaking valve stem seals...

190D22 · #7 08-03-2003, 12:14 PM

I run Shell Rimula 15W40 year round. Did fine this past winter with it, and it was a cooold one too. I changed the oil this week, and even after the first start up I noticed that she isn't as clacketty. This stuff has API service ratings of CI-4 and SL-4... On the bottle it says it's what truck fleets use. On the 2nd oil change with it, what drained out had some dislodged sludge, so it seems to be cleaning too. I haven't had any sludge since that oil change. What drained this time was nice and smooth. Over all, the engine runs better with this stuff (I've run it for the past 15,000 miles). I feel better running an oil designed for diesel engines. But, If I were to go out and buy a new, or a relatively new car with low miles (gas or diesel), I would most definately run full synth mobil 1.

I was going to use rotella, then I saw the Rimula sitting there. The guy told me he just got it in. It might be a new oil (as of a year ago). I would try this stuff.

jassz · #8 08-03-2003, 12:14 PM

Sorry, I didn't explain that very well. The thing with the hydraulic fluid was a whole other thread. We replaced the accumulators a couple of weeks ago. In anticipation I went to the dealership and picked up ONE litre of Mercedes hydraulic fluid (I had generic, but it was suggested on this board to get the real McCoy). Anyway, after the accumulators were on, and not leaking (there was a leak at first and a bunch squirted out), I checked the fluid level of the hydraulic fluid. It was at minimum. I added half a litre. It was STILL at minimum. I added the whole litre, and it was STILL at minimum. I assumed I just didn't buy enough, but it seemed odd it would show on the dipstick at all if it were so empty. I checked for leaks and there were none. Anyway, while I was scratching my head and wondering what was going on, I decided to check the oil. It was OVERfull. That pretty much never happens as we have the usual leaks and drips.

So, then I came crying to this board, askign if it was possible that the hydraulic fluid was running in to the crankcase, and I was told 'Yep, that's possible'. But I don't REALLY know if that's what happened. It's been running well, suspension works as it should despite being at minimum. But it did start smoking a bit more, and when we thought about it seemed like it may have started about the same time.

Quote:

or leaking valve stem seals

Yes, that's my guess.:p So back to my question. Would thicker oil smoke less?

leathermang · #9 08-03-2003, 12:27 PM

In the future, when you have good indicators that the oil MIGHT have been diluted you should change it out.. oil is really cheap compared to hard engine parts....

Gurkha · #10 08-03-2003, 12:50 PM

Apart from the best, Mobil-1, I find the excellent results with single weight, turbo approved Gulf XDMO SAE 40. Super stable after 500 miles of high speed and mixed traffic driving at 50c weather with a turbo charged OM-616.

MB engineers did a test a while ago and concluded that the best protection was offered by the use of single weight oils.

leathermang · #11 08-03-2003, 01:30 PM

For years the manufacturers of small gas engines have said to use STRAIGHT 30 wt for their engines because of the high stress conditions ( air cooled ) they run under...

Because of that I also use Straight 40 wt Delo 400 in my tractor and my MB's.

Of course, I am in an area where the lower temp viscosity is never a problem.... but I feel protected at the higher temps on 20 year old machines with more bearing clearance due to their mileage using the straight 40.

jassz · #12 08-03-2003, 06:04 PM

Quote:

I find the excellent results with single weight, turbo approved Gulf XDMO SAE 40. Super stable after 500 miles of high speed and mixed traffic driving at 50c weather with a turbo charged OM-616.

Well, so far I havent' been able to FIND that oil here.

Maybe because our moderate climate doesn't really call for it, so no one carries it?? I'm off to check a couple more places, but we may be sticking with the 15w40....

Gurkha · #13 08-03-2003, 10:54 PM

Have you tried checking with Gulf dealers and gas stations, they might be marketted under a different name.

Wes Bender · #14 08-04-2003, 11:09 AM

Natalie -

For sure, if you suspect that hydraulic fluid has contaminated the oil in the crankcase, it should be changed.

As far as the oil to be used, there has been so much posted on this forum that you should be able to pick what you want. Just make sure it is rated for diesel engines (i.e. the SAE rating begins with a "c" and not an "s").

For what its worth, I drive one of my 300D turbos between Tucson AZ and Alpine AZ regularly. Temps range from 110 in Tucson to the mid 40s in Alpine and I use Chevron Delo 400 15W40 - no problems.

Have fun on the trip,

Wes