Well, I suppose this is a good day for a first-post, and a favorite topic. My cars range from 1953 to 1994 models, a few interesting ones are: 1981 MB-240D, 440,000 miles on a rarely-mentioned oil, Exxon XD-3 15w-40 with factory filters (important-the factory part is a cartridge with full-flow and depth-type bypass stages). This engine has an oil thermostat set at 190F. Borescoping still shows crosshatch in the cylinders, and in fact, the OHC looks like new, just a little polishing on the nose of the lobes. Oil use is about 1 qt. for a 5000 mi. OCI, if I make it that far, otherwise 6 mos.
A 1990 F-150 with the 300 cid. straight six has 210,000 mi., trouble-free, same oil, Fram HP-1 or Hastings filters. Oil use is again about 1 qt. per 5000 mi. Performance and mileage are same as new for both. Both engines are clean, clean, clean. Shiny, bare-metal clean, nothing in the pans.
An interesting import is a bought-new 1964 Austin Healey 3000, 167,000 mi. on original engine. This 152 cid. six was born during that transition period between monograde non-detergent mineral oils and early multigrades with questionable additive packs. The engine was broken in with SAE 30 ND, then DX-3, an SAE 30 diesel engine oil, at 500 mi, a Cat series 3 oil as I recall, and then to the 15w-40 versions of DX-3 or XD-3 as they became available. Some of the early detergent oils run in friends' cars of that time led to cam failures in less than 2000 miles, due to corrosive wear enabled by the detergent's stripping of the varnish layer from cam lobes. ZDDP and barium and calcium sulfonates solved that problem once the mechanism was identified. But somehow, through the dark ages of oil formulation, the little 600-plus pound David Brown tractor engine survived all that and runs great today, very clean and doesn't burn too much yet ( I think, but it leaks a lot-no rear crank seal, just a slinger). This car has always had oil changes between 1000 and 2000 mi, just something to do when the oil starts being visible on the dipstick. Most of these engines had to be rebuilt at around 40K miles because of loss of oil pressure and compression. I think that not taking a lot of expert advice, dumb luck, and very frequent changes of high-TBN oil pulled this one through.
A recent hand-me-down is a 1994 Buick Regal, 168,000 miles, oil changes at some quickie lube, details unknown. Needed Techron, also ran a pint of xylene and a pint of toluene to finish what the Tech started, runs much better. But here, I'm on less familiar ground, reluctant to use my old standby 15w-40 this winter in Texas. Any recommendations for this 3.8 L V6? What do these engines seem to like (5000 mi. OCI is preferable, so I won't have to write antyhing down).
Thanks again to all for the interesting comments in the forums!
