Castrol GTX Classic with lotsa ZDDP

[Koizumi]

Since oil threads are prolific and polarizing… Forgive me but I had to ask:

Anyone running 20w-50 Castrol GTX Classic? This is a new offering for Catless (I run Catless) classic cars with high ZDDP.

I just switched to it since it took 2800 miles for Driven GP-1 to finally stop leaking (I change oil at 3k no matter what). Prior to this I was a Brad Penn guy for years.

PS. I run 20w-50 exclusively cuz where I dwell, it’s hot af!

[ADDvanced]

I looked into this, and it seems like a decent oil.... however.... VR1 seems like a better oil, and is cheaper.

https://bobistheoilguy.com/forums/threads/hydro-oil-m1-15w-50-vr1-20w-50-or-gtx-classic-20w-50.365777/

https://bobistheoilguy.com/forums/threads/valvoline-vr1-racing-vs-castrol-gtx-classic-20-50.358576/

https://bobistheoilguy.com/forums/threads/new-castrol-oil-for-the-classics-castrol-gtx-classic-20w-50.339113/

"Overall VR1 is probably a better oil, made with a modern SP additive pack with boosted ZDDP and more ZDDP than the Castrol, also the Valvoline is mostly Group II while the Castrol is mostly Group I, I haven't seen a full VOA of the Castrol but from the datasheet I know it has less ZDDP than VR1, and VR1 has a good VOA video here, I don't know if the Castrol has any friction modifiers but the VR1 does, I can tell that at least the Castrol probably has SN levels of calcium and not as much as some older formulation A3/B4 oils and CI-4+ diesel oils since it's .95% ash but I don't know if it primarily uses calcium detergents or if it uses a calcium/magnesium blend like modern SN+ or later lubes."

I bought another 6 pack of VR1 on amazon for $42
https://amzn.to/449Zh3r

So I'm sticking with VR1, my advice is worth what you paid for it.

[walt]

Here is the Castrol data sheet if anyone is interested.

https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/5C8B3B26A24C71DF8025867E0048CB89/$File/wepp-bybe5y.pdf

[Classic 911]

Following


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[Schulisco]

According to the datasheet of the Castrol GTX classic 20W50 contains 1400ppm zinc. This is the very upper limit for cars equipped with catalytic converters. They write that it isn't appropriate for modern cars due the high zinc.

[pmax]

Formulations do change.

But this is still dino oil, right ?

[Nditiz1]

$42 for 6 qts is decent but not cheap than 2 5qt jugs of Castrol for $20 from Walmart at least it was when I bought it a few months ago.

[Koizumi]

I paid $21 5qt. x2 via Amazon and 1qt. x2 free with using my $20 coupon from collecting points via AutoZone.

Am I correct in assuming it’s some sorta dino blend?

[slow&rusty]

I only Castrol GTX Classic, so exclusively and have been very happy with it. I buy it off Amazon or Walmart online.

[PeteKz]

I have spent years reading up on oil formulations and tests, and I think I know less about motor oil now than I did 20 years ago, and I'm a mechanical engineer! But I've come the conclusion that almost no one knows as much about oil as they think they do--including the engineers who formulate it. Why? Because they are always operating under constraints of time and cost.

One thing I do know with certainty is that the manufacturers regularly change their formulations, not just to meet newer specs, but also to cut costs. Thus, what you bought last year may not be the same product in the same graphics bottle as this year. Another conclusion I've reached is that the total oil formulation is more important than the amount of zinc/phosphate in the oil. Yes, even for solid cam/follower engines. The amount of zinc or phosphorus is a proxy for the ultimate lubricity of the oil, but not a direct measure of it, and newest SP formulations with moly and titanium additives don't need as much ZDDP. So don't think that is the most important measure. I've made that mistake too.

That said, the web site that I think provides the best brand-to-brand testing info on motor oils is run by a guy that goes by "540 Rat". He's an ME too, but pretty evangelical in his writing style, which always turns me off, but I can't find any better info. Certainly not at the oil manufacturers sites, which appear to be designed to provide the minimum info approved by their marketing departments.

Anyway, read the information for yourself. https://540ratblog.wordpress.com/

[HarryD]

Probably the best advice on this topic is to find a reputable AIR COOLED engine builder and see what he is recommending. These guys have seen plenty of motors and are aware of the issues.

Personally, I am currently using LiquiMoly High Tech Touring 20W-50. Why? Per their web site, it meets the requirements of "ACEA A3/B4, E2, Allison C4, API CG-4, API SL, Volvo VDS"

[pmax]

Caterpillar !

[Kraftwerk]

I am running Liqui-Moly 20W-50, but seriously considering going back to ol' Shell Rotella soon,
since Liquid moly is a PITA to source.

[HarryD]

Originally Posted by Kraftwerk

I am running Liqui-Moly 20W-50, but seriously considering going back to ol' Shell Rotella soon,
since Liquid moly is a PITA to source.

There is always Amazon. I am fortunate that my FLAPS stocks it.

[Koizumi]

Originally Posted by pmax

But this is still dino oil, right ?

I’m wondering as well. A blend of sorts perhaps? Anybody?

[Schulisco]

Here in Europe there's a Castrol Classic XL 20W50 engine oil available, I cannot find this for the US market, don't know if it's available in the US.
https://www.walshlubricants.ie/product/castrol-classic-xl-20w50/
It's intended for car's from the 60ies up to the 80ies.

The Castrol GTX (3) blend was afaik developed to fight against sludge in the engines which was a problem in the 70ies to 90ies. I expect the new GTX 20W50 to be designed for cars of same period as well, only with higher viscosity for cars like the aircooled 911. The highest GTX viscosity I know before was the GTX 15W40. There's another GTX 20W50 for high mileage engines according the Castrol worldwide website. Probably also a consequence of higher temperatures due to the climate change...!?

https://www.castrol.com/en_us/united-states/home/motor-oil-and-fluids/engine-oils/motor-engine-oil-brands/castrol-gtx-brand.html

They slightly differ in their values according to the datasheets. Unfortunately no more detail about the additives and the purpose.

When you read on the Castrol website it's clarifying a bit more:

WHAT ARE THE BENEFITS OF CASTROL GTX?
Superior protection against engine sludge*
Advanced protection against viscosity and thermal breakdown
Premium quality base oils and anti-wear additives to help extend the life of your engine
Helps minimize oil consumption
*When tested in engines with a high level of sludge

WHAT ARE THE BENEFITS OF CASTROL GTX HIGH MILEAGE?
Phosphorus Replacement Technology to help extend the life of the emission system
Superior dispersancy that fights sludge build up
Exceptional oil burn-off protection exceeding industry standards*
Seal conditioners to help reduce leaks
Advanced additives that minimize engine wear
Improved fuel economy**

GTX ultraclean is for modern engines and is a synthetic oil. GTX fully synthetic and Edge are synthetic oils for modern engines as well.

[PeteKz]

Originally Posted by HarryD

Probably the best advice on this topic is to find a reputable AIR COOLED engine builder and see what he is recommending. These guys have seen plenty of motors and are aware of the issues.

Personally, I am currently using LiquiMoly High Tech Touring 20W-50. Why? Per their web site, it meets the requirements of "ACEA A3/B4, E2, Allison C4, API CG-4, API SL, Volvo VDS"

Harry, I hear ya, but the manufacturers change their formulations regularly, so the stuff in the same bottle isn't the same now as it was a few years ago. And they don't announce those reformulations. That's why you can't rely on what you always used. The newer stuff probably won't cause a customer come-back on an engine within a few years, but may not provide as long life as other oils.

I don't know what the right answer is, but I do know that it keeps changing...

[HarryD]

Originally Posted by PeteKz

Harry, I hear ya, but the manufacturers change their formulations regularly, so the stuff in the same bottle isn't the same now as it was a few years ago. And they don't announce those reformulations. That's why you can't rely on what you always used. The newer stuff probably won't cause a customer come-back on an engine within a few years, but may not provide as long life as other oils.

I don't know what the right answer is, but I do know that it keeps changing...

Totally agree. The fact the LiquiMoly has an API SL certification gives me confidence it is a suitable old time formulation.

[Mr. Merk]

I just bought all that walmart.com had in stock (two quarts!) but went to Amazon and bought a two 5qt jugs for $21.99 ea

I also picked up a 12 qt case of VR1 single qt bottles for $82.35 (to take some with me on my 5k mile trip to Rennsport Reunion.)