Re: Dino juice

[zm@mhcnet.att.com (Zafer Mehmood [209])]

> 
>   My understanding is that the natural voscosity ranges of synthetics
>   negate the need for viscosity improvers and hence the wide range
>   and long drain intervals are possible. I let the Castrol GTX go for
>   ~5k mi in the ur-Q, where I only let the rotten dino juice go 2k mi.
>   I'll let the GTX go indefinitely in the '84 4KQ, unitl it's down a quart,
>   then change it, often >10k mi at ~160,000 miles. The QTW gets a
>   change every spring & fall, regardless of mileage, but well under
>   10k mi.
> 
>   -glen
> 


Glen,
	Castrol GTX is regular dino/fossil oil. Castrol Syntec is the
synthetic one. If you are running ~10K miles on dino juice on a turbo
engine, you are asking for trouble. May be you meant Syntec when you
wrote GTX? 

Synthetic oil does have broader viscosity range vs dino oil and resists
viscosity breakdown better, but I've read that viscosity enhancers are
definitely added to get a broad range such as Castrol Syntec's 45 (5W50).
The viscosity enhancers degrade over time. You are much better off with
using two different viscosity ranges for summer and winter use. This is
what I do. I run Mobil 1 15W50 most of the year on my two turbo cars and
switch to Mobil 1 10W30 in the coldest part of winter. I change the oil
and filter every 5K miles.

Zafer