Ladies and Gentlemen:

Summer's coming to Ohio and as it gets warmer outside the motor in my 245DL is more likely to make that diesel-like preignition ping under certain, predictable conditions. Amount of ping is directly(?) proportional to increase in temperature (ambient and internal) and engine load.

Is a little ping necessarily a problem? I remember hearing in the old days how a smidgen of spark knock under certain conditions meant that combustion and power were at peak efficiency. I admit I have come to like the sound (I rode in a lot of diesels in Europe years ago; the sound also reminds me of a very satisfied purring cat).

I do run 87 (86 sometimes octane for reasons of economy. I'm not in a hurry or carrying large loads in the vehicle. Am I being too cheap? Are things getting so hot up in the cylinder head that there'll be breakage or meltdown? I hear brand new cars making that same "rattle", I swear. Is compression up in all modern cars?

Finally, will cooling system improvements (e.g. new radiator, water pump, electric fan) really keep things that much cooler up at the head where all the pinging's going on? I do get great heat in the vehicle and don't need the A/C.

Frank Richards