First of all, lubrication-related failures are rare ... in cars which are reasonably maintained. So, that alone is not "proof" that Castrol is an exceptional brand.
I used to use Castrol GTX in my 1986 Escort GT ... but I got rid of the car before it had too many miles on it. Can't comment on whether or not the motor was clean after many years, etc ...
I used the Syntec in my 1990 Acura and 1995 Civic Coupe. I was initially impressed with the way this stuff tended to stay very, very clean but in the Civic, I switched to Mobil 1 and it became dirty quite quickly ... suggesting that M1 was cleaning up something the Syntec left behind. The car
did have a significant amount of varnish on parts visible through the filler cap, but nothing too distressing ... especially with 100,000+ miles on the odo.
So, I have a few beefs with Castrol, but nothing too personal:
1) The synthetic mess they started.
2) Their base oils at last check were Group II (good) but not as good as some ... Pennzoil and probably Chevron. So, among dinos, I would put a few ahead of it.
3) The shearing. I noticed this (and complained to
Patman about it. I asked if he ever saw a sample which made it to 3,000 miles
without shearing. he found a couple but the stuff seems shear happy nonetheless. I'm guessing that they WANT the oil to shear so they can claim/cite better fuel economy numbers. I don't like this approach. The oil should stay in grade throughout reasonable intervals. If manufacturers or others want to spec out thinner oils, that should be handled more openly/honestly.
So, I don't think it's a
bad oil, but it's not one of my favorite brands.
![[I dont know]](/forums/graemlins/dunno.gif)
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Bror Jace