No harm will come from switching back to mineral (dino) oil. As a matter of fact, I often switch back and forth on my Isuzu Rodeo. Due to a sticking hydraulic lash adjuster that makes the valve tick occasionally, I switch to a Mobile 1 0-30W oil for an oil change, which according to the factory is supposed to relieve the problem. The only thing is this: I don't care what the oil manufactor SAYS their oil can do for change intervals, I go by the manufacturer's recommendation for extreme service, which is 3500 miles. Changing with synthetic every time is expensive....

I have been very happy lately using Rotella 5W-40 synth, or Rotella 15W-40 dino oil, available at Walmart in gallon size.

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On the plains of hesitation bleach the bones of countless millions who at the dawn of victory, sat down to wait, and waiting -- died

Its a myth.

Usually the stores around here always have 15w-50, its the 0w-40 that seems to be hard to find sometimes which is what I use.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

I get my 0W-40 at the dealer, for about the same price as the independent parts dealers( if they had it ).

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2007 C 230 Sport.

My 86 300E with 233,000 miles developed a lifter tick, could not identify which one as the noise came and went, ran Marvel Myster oil thru the Dino oil with no improvement, changed to REDLINE brand 20/50 synthetic oil and the noise disappeared immediately and has not returned and that was 3 months ago.

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Jerry

2004 SL500 Black 55K Miles
2002 s500 Black 90K Miles
1986 300E Gold 233K Miles
1966 Twin Cessna 320D
1989 Jeep Cherokee 233K Miles
1994 Ford Van E150 399K Miles