This is a topic with a lot of opinions, and the rules are constantly
changing (witness the ZDDP
issue, which wasn't an issue a year or two ago).
Anyway, I've read it's not a good idea to mix viscosities, mainly
because you won't know what
viscosity oil you end up with; if you mix 10W and 50W 50/50 do you get
30W? Frankly,
I don't know. And all bets are off if you mix different multigrades.
I did a re-read of some of the oil FAQ sites I've bookmarked, and some
say it's OK to mix
viscosities, as long as it's the same brand of grades. Different
manufacturers use different additives
and if you mix, well, you've got a science project.
I also see that some recommend NOT to mix different brands of the same
vis, for the above-mentioned
reasons. News to me. The sites are mostly unanimous that you shouldn't
use additives (STP, motor
honey, etc.)
Anyway, I maintain that you find a brand you like--preferably one with
lots of ZDDP for our
Healeys--pick a viscosity/weight that's appropriate for your climate or
budget, change it often
and you'll be OK. I think good quality 20W-50 mineral is appropriate
for Big Healeys, unless
you live in a really cold climate and drive in the winter, where a
15W-40 might be a good idea.
bs
Frenken, Eric wrote:
> Bob (Spidell), what's wrong with mixing viscosities? I ask out of curiosity.
>I've done that now for a long time without any negative side effects on
>recommendation of an motor oil company.
>
> Eric
> Heinsberg/Germany
> 123ignition dealership
>
>
>
***************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
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