motor oil in the fuel - Page 2 - PeachParts Mercedes-Benz Forum

scottmcphee · #16 06-07-2011, 06:31 PM

Higher viscosity fuels burn quieter because they change the flame front pattern of combustion, effectively retarding the timing. Quieter in this case probably means less complete combustion. And not as much power. If you regularly dump "stuff" in your tank and change up the burn pattern, adjust your IP timing to get back toward the comfortable "knock" level a diesel should burn at. And you'll get back more power by doing this. Motor oil has more BTU but you have to give it a chance to burn completely to get the power out of it. Don't fool yourself with the quietness thinking it has anything to do with lubricity. A quiet running veggy burner is getting pistons and walls wet, leads to ring problems. Clatter is good in a diesel.

cjbrown · #17 06-07-2011, 06:48 PM

Quote:

Originally Posted by Stevo

I do like the sound of these engines on bio. B20 would still require viton hoses and replacing the fuel neck grommet now and then wouldn't it? Not that its even available around here but maybe I try it on my up coming trip down the cost. for sure I'll try some 2 cycle oil from Walmart.

I had put new factory hoses on mine last year as a matter of maintenance after getting the car, so I didn't bother with viton replacements again. Never had an issue. They did warn me when I signed up for the cardlock that it could be an issue with some rubber hose parts. But 20% generally doesn't pose a problem like extended use of B100 would.

The downside to adding oil is the potential for carbon in the combustion chamber and stuck rings. I would not run oil in my fuel. Part of 2-stroke maintenance is removing the the head, rings, and powervalve and cleaning out the carbon. I know, had MX dirtbikes for many years. Even outboard motors don't run near the hours you would put on a car engine.

If you spent the money for a synthetic it then probably would not burn. But then if you're going to spend that kind of money on an additive why not get something designed specifically for your application.

The Duramax guys did a fuel lubricity test with all the popular additives including biodiesel. Opti-lube was the top performer under biodiesel. If any one is interested in the report let me know and I'll dig up the URL for it.

The bosche injectors in the early d-max engine were especially temperamental and the majority wore out prematurely and would leak. Big problems with fuel in oil, super rich running, missing, and generally poor performance. GM extended the warranty on those motors to 7 years and 200K miles. Most got their injectors replaced under warranty but the design wasn't improved 'till later models so they tended to go out again and again. Water in fuel and lack of lubricity were contributing factors. Also due to the head design they were a ***** to change out so the total cost was four to five grand to do them. OUCH!!

Stevo · #18 06-07-2011, 07:47 PM

This is an interesting subject, oil additives to fuel, and I really dont want to stir up a bunch of poo here but is it commonly agreed that our 617/6s need more lubrication than the new fuels provide? Or/and Its just a matter of which does oil the best job? I have read so many pors and cons I dont add anything anymore and the cars run great.