Castrol GTX 20-50

-

Mojoe9955

Well-Known Member
Joined
May 14, 2021
Messages
594
Reaction score
384
Location
NJ
Anybody using this oil. I've always been partial to Castrol GTX oil. In the 70's worked in service at a big boatyard and a foreign car dealership and at both places that's all we used. Eventually I got into seriously working and spending less on hobbies, so I started getting my oil changed at the dealership or JiffyLube so it was pretty much whatever they have. Fast forward to today and I still get my y oil changed in my car and van, but I've been spending more time with my Mopars. A 69 b body big block, a 70 small block Duster and a 72 slant 6 Demon. To make a long story longer, I'm finding it hard to find a an old school oil for these cars, especially Castrol which in the 10/30 or 40 it all seems to be blended now. I did find this stuff and was wondering about your input on it. I'm going to use a Fram filter which was our go-to filter back in the day...that's another story though.

Resized_Resized_20220909_092202.jpeg


Resized_Resized_20220909_092209.jpeg
 
My dad religiously used Castrol 20W-50 in all of his vehicles, from what we'd call "classics" today right down to his 1990 3-cylinder Geo Metro. He owned mostly early 50's thru late 70's cars, mostly Fords, Chevys and Plymouths. Always great oil pressure to say the least and never, ever an issue related to oil... I think it even helped slow the leaks in his Fords with it being the thicker viscosity LOL.
 
My dad and I used to use Castrol 20/50 too. I use Valvoline VR1 20/50 now, but that looks good didn't even know Castrol made it.
 
Do you drive any of them in winter? It’s definitely a decent oil, and it’s got zinc. Cold starts in under 50* weather would be my only concern. Not catastrophic, I would just make sure to bring it up to temp before any spirited driving. Oil pressure gauge would tell you when you are good to go. I run 20/50 in my bikes and my Mopar’s, but they don’t see any cold weather.

I am convinced you can put anything from corn oil to bag balm in the slants crank case and it will run just fine.
 
I currently use Lucas 10/40 hot rod and classic in a Chevy 307, a B-Body 383 and the 340 in the Duster. I did however recently change the oil and put VR1 20/50 in the 383 when I was diagnosing an engine noise, thinking it may be related to oil pressure(didn't wind up being related to this after all was said and done). Couldn't find Castrol 20/50 on the shelf locally. Great oil pressure to say the least with the VR1 20/50.
 
My Dart has a roller cam so I'm not too worried about the oil for that, but I have an 85 Toyota Supra with flat tappets. I used the Mobil1 0w-40 Full Synthetic because I felt 50 weight oil would be too heavy. The 0w-40 has 1000 ppm phosphorous and 1100 ppm zinc, so it's probably fine.

Here's the link to the product guide. I'll also include the document so when someone finds this post 10 years from now and the link is broken they see what I was talking about

https://www.mobil.com/lubricants/-/...w-us-1/files/mobil-1-product-guide-rev-31.pdf
 

Attachments

  • mobil-1-product-guide-rev-31 (1).pdf
    122.8 KB · Views: 96
Castro makes great oil. Wish they made this in lower viscosity.
I agree, BUT everyone I've ever known that uses 20/50 like there was no other oil in the universe had great service from it. I'm going to try it on Vixen's upcoming oil change.
 
Anybody using this oil. I've always been partial to Castrol GTX oil. In the 70's worked in service at a big boatyard and a foreign car dealership and at both places that's all we used. Eventually I got into seriously working and spending less on hobbies, so I started getting my oil changed at the dealership or JiffyLube so it was pretty much whatever they have. Fast forward to today and I still get my y oil changed in my car and van, but I've been spending more time with my Mopars. A 69 b body big block, a 70 small block Duster and a 72 slant 6 Demon. To make a long story longer, I'm finding it hard to find a an old school oil for these cars, especially Castrol which in the 10/30 or 40 it all seems to be blended now. I did find this stuff and was wondering about your input on it. I'm going to use a Fram filter which was our go-to filter back in the day...that's another story though.

View attachment 1715982894

View attachment 1715982896
Anytime is says "will harm catalytic converters".... it has what you need for a flat tappet cam.
 
I'm in Florida (always hot) so the 20/50 makes sense here.
 
My dad and I used to use Castrol 20/50 too. I use Valvoline VR1 20/50 now, but that looks good didn't even know Castrol made it.
It's a re-issue. A good idea, I think.
 
Anybody using this oil. I've always been partial to Castrol GTX oil. In the 70's worked in service at a big boatyard and a foreign car dealership and at both places that's all we used. Eventually I got into seriously working and spending less on hobbies, so I started getting my oil changed at the dealership or JiffyLube so it was pretty much whatever they have. Fast forward to today and I still get my y oil changed in my car and van, but I've been spending more time with my Mopars. A 69 b body big block, a 70 small block Duster and a 72 slant 6 Demon. To make a long story longer, I'm finding it hard to find a an old school oil for these cars, especially Castrol which in the 10/30 or 40 it all seems to be blended now. I did find this stuff and was wondering about your input on it. I'm going to use a Fram filter which was our go-to filter back in the day...that's another story though.

View attachment 1715982894

View attachment 1715982896
Not trying to open a new topic on the OP's thread, but, engine oil viscosity is determined by the internals bearing clearance's. Not by what looks good on the store shelve or what the other guy's are using.
 
Not trying to open a new topic on the OP's thread, but, engine oil viscosity is determined by the internals bearing clearance's. Not by what looks good on the store shelve or what the other guy's are using.

Don't forget ambient temperature and application. An 8.5:1, 318 in a snow plow in winter isn’t going to use the same viscosity as a 10:1, 318 A body doing burn outs in 100* weather. Same tolerance/clearance but different application and ambient temp.
 
Have to disagree with post #19. Oil viscosity is determined by the oil, not brg clearance. Brg clear determines oil pressure.
 
I also have disagree with his comments about picking my oil based on "what looks good on the store shelf or what the other guys are using"
My post was more about brand loyalty and the search for a conventional oil as opposed to a blended or synthetic oil.
 
Re-stating what MidnightSwinger said, just remember that if your engine is still covered under the manufacturer's warranty, you've got to use the grade and weight of oil specified by that manufacturer or your warranty will be void. If you have a newer engine that is supposed to use 0W-20 oil, for example, I have heard of cases where there was insufficient oil flow when the owner tried using heavier oil, and the pistons scored the cylinders. The manufacturer would not honor the warranty under the circumstances.
 
Re-stating what MidnightSwinger said, just remember that if your engine is still covered under the manufacturer's warranty, you've got to use the grade and weight of oil specified by that manufacturer or your warranty will be void. If you have a newer engine that is supposed to use 0W-20 oil, for example, I have heard of cases where there was insufficient oil flow when the owner tried using heavier oil, and the pistons scored the cylinders. The manufacturer would not honor the warranty under the circumstances.

That may be, but I personally get rid of that light oil as soon as I can. I run 10W-30 in my Dodge Hemi's. That is as light an oil as I will go. All three still run like new. The 2001 Jeep Cherokee and the 1996 Neon have had a life of straight 30 or 20W-50 in the winter. All well past the warranty period and as above, still run like new. Not sure what the motive is for using light oil. Saving Gas? I'd rather my engines last as long as possible.
 
-
Back
Top