A fairly nice article although it was mostly stuff I already knew from
testing motor oils and fuel in Colombia back in the 80s.
But the reason why I am replying is a similar problem I had about two years
ago. I usually change to 10W/40 in the winter. I bought a case of Castrol
GTX and found the 10W/40 oil was clear (like water) and appeared very thin.
I was convinced the oil was bad, but the store I bought it from said they
had heard of no problems. My BGT ran fine with it in there although the oil
pressure appeared to run maybe 5-10 psi lower than normal. Since then, the
Castrol has always come in its normal darker color though. I can only guess
that there was a change in the supply of crude at the time but hope that
Castrol kept its normal specifications on the oil.
Pour point is a big factor here - when it gets in sub-sero temps here
(Montana), oil doesn't flow at all. Never keep spare containers of oil in
the car during winter - you can't get it ou
David
67 BGT
72 B (restoration in the midst)
At 10:48 AM 12/24/2001 +0000, paul.hunt1@virgin.net wrote:
>Speaking of changing oil I only noticed a couple of changes ago that GTX in
>the UK has changed from 15W/50 to 15W/40. Might be my imagination but the
>engine seemed to sound more rattly than usual when hot with it. Decided to
>see if there were any other 15W/50s in Halfords and found two - their own
>brand and Duckhams Q. Couldn't quite bring myself to go for the own-brand
>so got the Duckhams. The first thing I noticed was that it seemed
>significantly thicker out of the can than I remember the GTX. 2nd was that
>the cheapskates only put 4.5 litres in instead of 5. But the bad news is
>the time the oil pressure gauge takes to rise from cold now. OK, it is a
>factory V8 which are well know for having a slow gauge, and we have ambients
>of 30/40F at the moment, but this is ridiculous. The only good news is that
>the hot idle is noticeably higher, but as I say it is winter.
>
>Even though this oil has only just gone in I'm thinking of changing it
>again, but what for? Any better-flowing 15W/50s out there? If I have to
>settle for a /40 then maybe I should go for Shell Helix Super at 10W/40. Or
>even Mobil 1 at 5W/40 (although it also seems to be available as 0W/40 and
>5W/30). My daughters Metro was supposed to use 10W/40 as I remember, but it
>had the consistency of water and leaked past oil seals, whereas GTX didn't.
>Can I expect similar, or worse, leaks with the Shell and Mobil?
>
>While searching for info I came across the following which I pass on:
>
>More Than You Ever Wanted to Know About Motor Oil
>by Ed Hackett
>http://www.rconcepts.com/beard/dragnet/drag/oilinfo.html
>
>And the home page has another link to a page on Octane.
>
>PaulH.
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