SDL/603 Soot Production
 

Just got a 1986 300SDL...am wondering, generally speaking, how the soot production of its engine would likely compare to that of my 1992 2.5 Turbo. My reason for asking: I did an oil analysis on the 1992 and found that I could easily go 10-15,000 miles before changing the oil. I'd like to aim for reasonably long drain intervals with the SDL, but I suppose I'd be cautious if it is likely to produce significantly more soot. I'll be using Mobil Delvac 1 synthetic.

Thanks.

bigger motor, older motor, bigger pistons, more soot.
it depends on driving style, filters and oil used.
get fresh oil in there, drive it 3K change the oil, drive another 3K and analyze it, or wait 6K and do it, 3 won't show much unless there is a pretty bad problem.

Well since they are just about the same engine, soot loading should be similer.

I think Dave (GSXR) goes 10kish miles, and I beleive Brian does his every 7k or so.

Analyze all you care to, come to whatever conclusion you feel safe with... but when in doubt, oil changed too frequently is a far better circumstance than oil changed too infrequently.

Well, Delvac 1 can handle up to 4% (even though MB "officially" recommends that soot levels not exceed 2%...presumably taking into account the capabilities of most oils). Does anyone out there have any evidence of soot levels from this engine at, say, 7500 or 10,000 miles? I realize that a number of variables come into play, but some ballpark numbers would be helpful.

FWIW, on my 1992 the soot level was 0.8% after 7500 miles. Mixed city and highway driving.

Have you thought about installing a bypass oil filter system?

I play it safe...every 5000 miles I change my oil. I use Mobil 1 synthetic Truck and Turbo oil. 5W-40. My car is a 1986 300sdl with 110,000 miles on it.

John

It's the same engine with one more cylinder.

If you had to start with a basepoint, I'd say figure the fuel consumption of the 602 would produce similar amounts of soot to the same fuel consumption in the 603. Or, if (for example) it takes 2,000gallons of fuel to get the the 1% point in the 602 it should take about 2,000gallons to get to the 1% soot point in the 603. The SDL/603 being a heavier car with an extra cylinder will mean that you get to that 2000gallon 1% point faster.