Best Oil? Synthetic? - PeachParts Mercedes-Benz Forum

dnthomas · #1 06-02-2002, 01:06 AM

Wondering what suggestions you had for oil in my 91 560SEL? I know that this will probably garner differeing opinion and most intrested in wither or not synthetic oil was ok? and any concerns going from a "regular" motor oil to a synthetic.

Mike Murrell · #2 06-02-2002, 01:21 AM

I hate these oil posts, but will respond anyway.

You have a '91 model W126 car. Same as me, just a bigger engine.

I've used conventional oil for many years and have taken more than one car past 300K with it. I used synthetic oil once(don't ask me why) and all it did was create leaks. It's known for doing this; however, in it's defense, it may be less likely to do so in the cars it was intended for - newer models.

Use a Mann, Mahle-Knecht; Hengst oil filter and the prescribed amt. of oil(conventional in my opinion). Do as Larry Bible suggests, changing it hot and often. The oil in my MB gets drained every 1500-2000 miles.

dnthomas · #3 06-02-2002, 01:49 AM

Yes I know these post are hated, now. I committed the cardinal newbie error and did not thouroughly do my search.

However, I hoped that my question was a little more specific and you answered quite nicely and thank you. I basically want to know what concerns, if any, if I change the car to a Synthetic Oil and if I could just change to it if I wanted or did I need to follow some procedure to complete a changeover to synthetic. This was prompted by a discussion with my brother in law who works at a Chevron refinery and he talked to me about Synthetic oil when he saw my new, to me, 560SEL. Of course he talked over my head about oil but the gist was the rate of breakdown of regular oil vs. synthetic and the fact that he thought that the changes could be made a little less frequently with synthetic oil and this would negate the price difference.

I am having no problems with the car now and lord knows I don't want any!

But wanted to treat it the best I could. So I would still like replies as to synthetic vs. regular but recognize that a discussion of brands may end up being the bulk of this trhead.

MikeTangas · #4 06-02-2002, 03:01 AM

Well, here's what I did on both the Suburban and the 560. I switched to Castrol Syntech semi-synthetic with no problems at all. I have logged almost 10K miles on the Suburban and over 4K on the 560 with no leaks. The 4.5 still runs full dino oil.

I was worried about possible leaks when I did the Suburban but those worries were gone by the time I got to the first oil change. My plan for the 560 is to try to switch to full synthetic at the next oil change.

dnthomas · #5 06-02-2002, 04:12 PM

Thanks Mike, I somehow suspected you might (and hoped) you would reply. Hope the 560 project is coming along great, I learned much from your posts. Thanks again

#6 06-02-2002, 09:26 PM

No engine manufacturer (including Mercedes) recommend/allow extended oil change interval while using Synthetic oils instead of conventional oils..
Your car has been performing well for several years with dino oil, don't expect it to perform better (or worst) with synthetic.
There has been some very well designed and very successfull marketing campain trying to push synthetic oils in the market.
Synthetic oils are good and perform better in certain extreme conditions, (very rarely encoutered in normal driving) but I rather have my engine bath in frech mineral oil than in 10,000mi old synthetic oils. If you don,t mind the cost, spend the same money in more frequent oil change. Your engine will thank you over the long run
Just my informed opinion.
JackD

Mike Murrell · #7 06-02-2002, 11:53 PM

Amen Jack!

Synthetic = Hype

As Larry says, change it hot/change it often.

MikeTangas · #8 06-03-2002, 12:57 AM

I think y'all misread what I wrote. I never said anything about extending the oil change interval, I said I have logged 10K miles on the Suburban using semi-synthetic and that I had worries which were gone at the first change.

In that 10K the Suburban has logged, it is now on it's fourth fill of semi-synthetic and the 560, after 4K is on it's second. I guess I didn't make that clear enough to begin with.

Still running at 3K per oil change on all my cars.

rickjordan · #9 06-03-2002, 11:26 PM

I second Mike's idea of gradually switching. Start first with semi and if your engine doesn't show signs of leaks, switch to full. I generally think synthetic oil is for high reving/turbo engines. Where the oil gets really heated up. Personally for a V-8 as large as yours I would just stick with the "change it hot and often" principal, using a good conventional oil such as Castrol GTX. It's really a personal decision, what ever makes you feel comfortable.

#10 06-04-2002, 08:41 AM

Quote:

Originally posted by dnthomas
I basically want to know what concerns, if any, if I change the car to a Synthetic Oil and if I could just change to it if I wanted or did I need to follow some procedure to complete a changeover to synthetic.

If you take your car into the MB dealer for an oil change and don't specify what brand/type of oil to put in, they will use Mobil1. If it's good enough for MB......???

csnow · #11 06-04-2002, 09:27 AM

I have found that synthetics are consumed at double or more the rate of conventional oils. This observation has been consistent across a wide variety of vehicles of all different ages.
That means that if your level does not fall all the way to the Low line between 3K mile oil changes now, you may need to add at least a quart between changes if you switch.

When I was a teenager, the motor on one of our shared family cars (Japanese) was run out of oil and destroyed spectacularly. Why? I decided to treat it to a synthetic oil change, and went away for 3 months. It was driven about 3500 miles in this time, and it ran completely out of oil one day. This car had never needed any oil between changes before. Of course, no one had bothered to check the level in my absence...

My point is that if you switch to synthetics, remember to watch that dipstick very carefully. A slight reduction in wear means nothing if the sump goes dry...

royaiii · #12 06-04-2002, 02:03 PM

Remember that once you change the oil of your car, you are removing all the crap that has contact w/ the oil. The oil itself will last for 20,000 miles but the crap that goes inside the oil makes the oil bad. Slight amounts of water could be inside causing rust. Ash of fuel burning.
I use synthetic in my new cars but I wouldnt waste the money for synthetic in my 300E. I just put a bottle of Mobil 1 in the 300E, for the extra startup protection.
If I were you, I wouldnt be putting Mobil 1 in my car. Try Valvoline MaxLife or run a blend of dino/synthetic like me,

royaiii
2001 S600
1999 S420
1997 E320
1996 SL600
1989 300E

tvpierce · #13 06-04-2002, 02:26 PM

It is my understanding that the "leak problem" with early synthetics was attributed to the base stock used to make the oil, and the fact that it didn't react well to some gaskets.
And I was under the impression that all manufacturers stopped using this formula -- so leaking as a result of changing to synthetic should be a thing of the past.

I am by no means an "oil-ologist". I'm just living proof that a little bit of knowledge can be a dangerous thing.

Jeff Pierce

jay123 · #14 06-04-2002, 02:45 PM

From what I've read on the web, the base stock comment is correct. However, if you already have oil leaks and old/worn gaskets, synthetic oil will make it worse. If you have no oil leaks, you should be fine. I'm using Mobil1 15W-50 in my 300SDL. No leaks or lose of oil. My car now has 220k. Better start ups, increase in fuel economy are some of the things I've seen so far. Dipstick is clean also. Not as dark as the dino oils used in diesels. preference is the key. There are numerous colors in the rainbow. Take your pick and stick to it.
I change my oil every 6k and the filter every 3k.

190D22 · #15 06-04-2002, 02:56 PM

In my 190D 2.2, mercedes changed my oil last. It was almost immediately looking black on the dip stick. Is this just the nature of diesels? This is the first time I've changed the oil in this car, I haven't owned the car very long.

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