Using synthetic oil(Mobil 1), in my '86 300SDL, changing the oil filter every 5,000 miles how long can I go without changing the oil. With diesels does the soot builup in the oil become a factor in determining oil change intervals?

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jcciem
'94 SL5000 60,000
'91 350SDL 545,000
'91 350SD 197,000
'00 E55 AMG 77,000

There is a lot of information in the diesel section, a search can bring up a lot of information. I do 7500 changes on mine with Mobil 1, no need to change the filter more often than the oil, it won't do much good. Anything past 5000 miles and you should verify with oil analysis. Both 0w40 & 15w50 are acceptable, the x-w30's are NOT.

Brian

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Brian Toscano

If you're going to use Mobil One in a diesel, you would be much better served to use Mobil Delvac One. It is blended for a diesel to provide much better soot dispersal. If you are going to use regular Mobil One, you need to stay with relatively short change intervals due to the lack of soot dispersal capabilities.

BTW, make sure you heed Brians warning regarding the X-W30's, they are just too thin unless you live in Fairbanks.

Good luck

I use 15W-50 Mobil 1 in my 300SDL. I change out the oil every 6k and the filter at 3k to keep the oil clean. Filtration is very important to oil life.

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99 C230K Sport
87 300SDL
81 300SD

What's the deal with oil in any diesel getting so dirty so quickly? Mine is dirty within a few miles of an oil change. This is true for all diesels, so I assume it's normal and not indicative of viscosity breakdown, etc.

I know that the Army hardly ever changes the oil in their humvees (seen it done ONCE in my seven years of service). When they do, it's only after an OK from an oil analysis lab.

I haven't got the money do spend $45 to $50 beans every 6k for an oil change, so I use Rotilla. They now have a synthetic version, but I know nothing about it.

Many people experience more severe oil seepage (more than normal) with a high mileage diesel (like the 123) when switching over to a synthetic. Another reason for me not to risk it.

Synthetic oils are definitely better, but I figure thousands of truckers use Rotilla and get half a million miles out of those engines easily, so what the heck.

Any thoughts?

Gil

Everyone needs to check this web site for all your answers concerning syn and dino oil:

http://www.carjunky.com/news/motor_oil_myths.shtml

Very cool site with plenty of info....

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99 C230K Sport
87 300SDL
81 300SD

changing the filter ever 3kmi is NOT very useful with synthetic. a lot of what the filter catches is viscosity improves, etc as mineral oil shears down and decomposes after 3kmi. syn fluids don't have this problem with such short drain intervals. i change my 15w50 and filter every 7500 miles. mobil 1300s and chevron del 400 are better than rotella and even slightly cheaper. comparing heavy duty diesel, direct injected trucks with 44 qt sumps, multiple filters, and run at 1700 rpm (redline 2400) to indirect injected MB light-duty diesels than ran 2500-5000 rpm is not a good idea.

Brian

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Brian Toscano

I change the oil on my 300SD every 2,500k-3,000. Are you saying that it is not neccesary to change the oil that often?

MD:

Thanks, I hadn't considered the massive amounts of oil and filtration involved in a semi engine. It definitely isn't the same animal as a 3 liter Benz engine, to say the least.

So, you think the synthetics are worth the price, then. I still didn't catch your point about not changing the filter every 3k. How long, with regular oil changes at (3k-?) can you let the filter go before changes?

Also, is there anyparticlar brand of filter that stands out for these cars? I ususally try to go with Napa (Wix) as they are rated very good, but it seems as though no matter who sells the filter, it's made by the same factory in India, and doesn't seem all that substantial.

What about Mann, the original equipment manufacturer of most German car filters?

Thanks in advance,

Gil

Sorry for my bad grammer in the last posts.

I buy Hengst, Mann, or Knect filters from Mercedesshop, dealer, or ebay - really whomever has the cheapest price at the time. These filters are readily available for $6-7 so I see no reason to buy anything else.

The main reasons oil is changed at 3000 miles (if I were using mineral oil, I'd do it at 2500) is because it starts to fall apart. The main reason to change a filter at 3000 is IFF you are using mineral oil, the filter is catching the oil fall apart. If you use synthetic, you dont have either problem.

So, if you want to be VERY conservative, just change your synthetic oil at 5000 miles along with your filter. Buy oil that is CI-4/CH-4 rated, or Euro spec B3/B4. Some oils are MB 229.1/229.3 rated which is even better.

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Brian Toscano

Maybe this will help for more info on oil filters:


http://members.nbci.com/minimopar/oilfilterstudy.html

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99 C230K Sport
87 300SDL
81 300SD

If you are using mineral oil (non-synthetic), change every 3000 miles, a filter every or every other change. This system had kept the chevy work van running for 299,000 miles, should keep a Benz running forever.

If you use synthetic (Mobil 1, for example, as it isn't particularly recommended for extended service), 5000-7500 mile intervals is fine, but change the filter every time.

If you are changing from dino oil to synthetic, get an extra filter and change it after 1000 miles. You can leave the oil in, but the filter will contain all the crud the synthetic oil cleaned out of your engine!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!