Tom Walker wrote in a message to Roy J. Tellason:

-> RJT> Feel the difference in the oil?  

-> WC> Sure, used to change at 3,000 until I noticed. Bikes run hotter 
-> WC> than car engines, at least the air cooled ones do. After I noticed 
-> WC> the change in viscosity I checked the dip stick after 2,500 until 
-> WC> I hit the economic - maintanance sweet spot of 2,800 miles. I 
-> WC> always used Castrol 10 - 40 or 20 - 50 whichever the manufacturer 
-> WC> recommended.

-> Hmm.

 TW> I am a Castrol 20-50 man myself.

I've gone through cases and cases of that stuff.  

 TW> I just bought a 1998 Chev S10 Pickup and note that GM strongly 
 TW> recommends against using any oil heaver then 30 Weight. 
 TW> Interesting, Cannot immagine why.

Tighter tolerances?  Beats me...  I know that with most of the stuff I have
that has lots more miles on it I go with the 20W-50,  too.  The one car
hasn't gone that far up there yet,  so we still put 10W-40 in that one, 
for now.

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