I have a '95 SL500 with less than 53,000 miles. As you can guess, it does not see much use. Taking it out yesterday (sunny, temps in the low 40s), it began to run roughly at idle in Drive and shook a lot when starting off from a stop. Warm idle was running an indicated 500 rpm.

I got where I was going with the engine running roughly. When I returned to start the car again fifteen minutes later, it would not start. I cranked it twice for five seconds each time. I walked away, returned twenty minutes later, and it fired right up. The roughness at and off idle was still there.

I drove it for a while, and after about fifteen more minutes the roughness was gone. At no point through this did I get any warning lights on the dash, oil pres and water temp were fine.

The car usually requires a bit of cranking (say, three seconds) to start normally.

One other area of concern is oil pressure at warm idle in Drive. I have 5w30 Amsoil in the crankcase, and at a 500 rpm warm idle, my oil pressure is just over 1 bar. I do not hear any ticking from the engine, so I am not sure about going in to change the oil guides in the heads. Pressure goes right up to 3 bar as soon as the rpms go up a bit.

So, without throwing parts at it, was this just a fluke? A shot of bad gas? A bit of sulking on the part of the car because I don't use it enough?

Thanks!
Robert