Put the 5 quarts of FREE! 10W-30 from the LAST MaxLife deal in the SVX for a 3K test run (vs. my old standby, $0.49 per quart Chevron Supreme) and I must admit there does SEEM to be a little less oil showing around the valve cover gaskets, which have been showing a minute amount of oil for, OH!, the last 4 or 5 years.
Since it costs anywhere from $200 to $400 to have them replaced in place (somehow it is MUCH easier to replace them with the H-6 engine out of the chassis?) I think I can put up with losing an ounce or two between OCI's for another 4 or 5 years...
Anyhow, it seems to work OK, haven't noticed any change, oil stays nice and clean, etc.