Viscosity is just one oil characteristic.
Assuming that the manufacturer specific approvals ( MB229.x, VW50X.XX,
BMW LL-01, or whatever, for example), are met, If ( again, example)
10W-30 is spec'd, then 0W-30, 5W-30, 10W-30 are all fine.
The mfr specs involve the composition of the additive pack, and reflect
concerns about corrosion, sludge, specific metal wear, emission control
longevity, oil endurance, etc.
I don't know of any one place on the web to reference the ratings and
approvals, but it must exist, I guess.
| > Of course, 5w-30 is no thicker than 0w-30.
| > Don't work the wrong end of the number.
| > Any xxW-30 is the same viscosity as any other xxW-30 at operating
| > temperature.
| Incidentally, is there anywhere on the web an idiot's guide to the
| numbers? In particular, supposing your car's manual says you should be
| VW yyy 00, but the shop has zzz 00, that might be "better" or "worse"
| it's not always easy to tell.
| Also is it safe to assume that 500 00 [or whatever] (1/97) is better
| 500 00 (1/92) - i.e. are the later dates always a more exacting
| Again, I presume that zzz 01 is always OK if zzz 00 is specified, but
| only my assumption.