Castrol GTX Classic vs Valvoline VR1

[AUSMHLY]

Castrol has a high zinc, high phosphorus 20W-50 conventional oil.
It appears to have the same Zinc 13% and Phosphorus 12% as Valvoline conventional oil.
Currently, March 2023, there is a bit of a price difference for the 5 quart amount. Castrol $24.22, Valvoline $36.99
What advantages does one get using the higher price Valvoline?

Castrol GTX Classic SAE 20W-50
13% Zinc and 12% Phosphorus

Valvoline VR1 Racing SAE 20W-50
Zinc 1,300 PPM and Phosphorus 1,200 PPM
13% Zinc and 12% Phosphorus

 

[Bob_Spidell]

I've got enough VR1 and filters to do nine oil changes--@ 7qt/change plus top-ups--that I've bought on sale over the years. TBH, I think I'd rather have the Castrol (though I don't recall seeing it at local parts houses). The issue, I think, with 'racing oils' is they may not have enough viscosity improvers/maintainers to prevent shearing of the oil molecules over time since they're formulated to be changed after every race (granted, a race might be equivalent to a couple thousand easy road miles). I loaded-up on the VR1 when it looked like high-zinc oils might get pulled from the market--they were for a period in California years ago--but Castrol is a time-proven producer of auto fluids and will work at least as good as Valvoline. Really, I'd likely buy whichever one was on sale when I needed it, and mixing the two should present no issues.

 

[kozelding]

Mobil 1 15w-50 — full synthetic with 1320 PPM zinc, 1200 PPM phosphorus

> Mobil 1™ 15W-50 | Mobil™ Motor Oils <

 

[Legal Bill]

Does your engine have any oil leaks? I find the Valvoline reduced drips dramatically.

Do you worry about low oil pressure when the engine is hot at idle, especially after long highway speed runs on a warm day? I find my oil pressure at idle is a bit higher with Valvoline.

Today I am changing out the Castrol Classic and refilling with Valvoline. With all well respected modern brand name oils of the same or similar viscosity, drips and oil pressure are the two most important things to me. I'm not worried at all about the oil's ability to lubricate or molecular shearing. Our engines redline at 5500 rpm. Modern cars are all redlining at or over 6000 rpm. My Honda S2000 redlines at 9000 rpm. Those are the neighborhoods where I really worry about oil breakdown.

I'm always willing to give something a try. But so far, Valvoline has been the best for me.

 

[AUSMHLY]

Today I am changing out the Castrol Classic and refilling with Valvoline. With all well respected modern brand name oils of the same or similar viscosity, drips and oil pressure are the two most important things to me. I'm not worried at all about the oil's ability to lubricate or molecular shearing. Our engines redline at 5500 rpm. Modern cars are all redlining at or over 6000 rpm. My Honda S2000 redlines at 9000 rpm. Those are the neighborhoods where I really worry about oil breakdown.

I'm always willing to give something a try. But so far, Valvoline has been the best for me.

LB, what Healey model have you?
I see you're in Boston. I used to live in Dighton MA.
How to speak MA... repeat after me...Wicked. (upgrade, Wicked Pissar)

I'd be interested in your real world comparison of 20W-50 Castro Classic vs Valvoline VR1.
Cheers.

 

[Legal Bill]

BJ-8. I didn’t see much difference between Castrol Classic and Castrol GTX with a tube of ZDDP additive. The drips are faster and maybe even more plentiful as compared with Valvoline. My engine was machine shop built by Custom Automotive in Weymouth, someone my Brother’s British car shop used for decades.
If you lived in Dighton and you love British cars you either know or are Dereck Durst.

 

[Randy Forbes]

I'm a faithful Castrol fan, have been since 1973 and my first MGB. I've had the opportunity to teardown/rebuild engines that I've put a lifetime's worth of regular interval Castrol oil changes through, and the insides can be cleaned off by wiping a paper towel on the surfaces; never any buildup of sludge or deposits. In all the engines that I've ever used__over the past five (5+) decades__I've never experienced an oil related/lack of lubrication failure. I'm convinced, and I'll be sticking with Castrol.

Didn't hurt that when I started messing around with BMWs that Castrol was their recommended brand (in the US, the ONLY place you could buy the prescribed 10w/60 TWS Castrol for certain ///M engines was at BMW dealerships). In more recent years, they shifted to a Shell* oil, but I'm led to believe it had more to do with cost saving than any longevity/reliability concerns.

* Much like Bob, when BMW switched their allegiance, I bought out the remaining stocks of Castrol 10w/60 TWS from the local BMW dealerships. I expect I have enough to satisfy the needs of our gray car for at least as long as I'm capable of doing the maintenance myself.