One Possible Oil Choice

I’ve been using Valvoline VR1 Racing 20W50 Synthetic for the high ZDDP content. Ran this by Brian Crall a couple years ago and he thought it was appropriate.

 

I've been using Castrol GTX in my 308QV, good ole dinosaur oil, due to alot of feedback that synthetic oils tend to leak through oil pan gaskets on our older cars. Along with ZDDPlus which claims to have 71,800 PPM of Zinc per 4oz bottle that covers 5 quarts of oil.


https://zddplus.com/

 

ZDDP – that old chestnut - modern synthetics, particularly the thinner one ( 0W-30 ) suffered a reduction from around 900 to 6-700ppm but is not suitable for older higher revving engines, leakage being one.

Bear in mind its not just the zinc, but modern formulations have much higher strength base oils and other additives in balance as well so the oils are much better than the older mineral based oils, even they are better than what was produced many years ago.

If you think about zinc – adding more doesn’t increase the protection, but in effect makes the protection longer lasting. To use a simple analogy – imagine the ZDDP as thousands of tiny firemen floating round in the oil – as long as the oil does its job and keeps all the metal components apart, they are not needed, so it doesn’t matter how many firemen you have. However, if you get a break in the oil film which allows metal to metal contact – a fire starts and the firemen all rush to put it out ( the zinc activates and creates a sacrificial non weld surface at the point of contact – so protecting the metal ) during this exercise, some of the firemen are lost, but there are still plenty of firemen in the oil to last the service life of the oil. So, having more firemen doesn’t mean its more protected, just they last longer in service ( if they are needed at all ) Actually having too much zinc is worse than not enough as it can create pitting on certain metals.


CASTROL EDGE 10W-60 is nominally 1000 ppm. This is the oil I use.

I wrote to Castrol many years ago as I wanted expert technical advice, I was fed up with conflicting information from grease monkeys:

The data I have from 1973 suggests “ Heavy duty motor oil ( Classic ) 15W-50 “. Looking back in my old recommendation charts Ferrari is absent until the 1990 when we started suggesting Castrol Syntron –X for all Ferrari models. This was likely one of the very first synthetic oils. The following years it went to Castrol Formula RS which was a full synthetic 10W-60.




For older cars such as yours we normally suggest the 10W-60 as the best option – it’s gone through a few revisions, and the latest variation is called Castrol EDGE Supercar 10W-60. It is a full synthetic and uses the latest Titanium strengthened base oils for the best possible performance and protection – and is standard fill in Koenigsegg, Audi R8, Bugatti Veyron, Aston Martin to name a few.




The Supercar would in my opinion be the best oil you could use and would offer excellent cold start properties, being a 10W would allow easy cranking and fast starts – with faster transition from boundary to full film lubrication. At working temperatures the 60 offering a slightly thicker fluid film between all the moving surfaces, but being a synthetic, the frictional characteristics would be less than a basic mineral 50 grade so would flow better and be more efficient.


Also the full synthetic would keep the engine cleaner and be more resistant to breakdown under temperatures and loads.




If the engine has been well cared for, and isn’t worn or full of sludge or deposits, then I see no reason why a modern full synthetic is not desirable as it is derived from mineral base stocks originally. And is fully compatible with the old classic 20W-50 mineral so will be no more an issue with seals etc than a mineral or part synthetic would be. If the engine is worn and uses a little oil, the extra viscosity of the 10W-60 may also prove beneficial




Of course, if you do not want to use a full synthetic and have a preference for a more basic oil – then the other options as I see it –




Castrol Power 1 4T 15W-50. This is a part synthetic oil designed primarily for motorcycles – BMW boxer twins mainly – however, it carries an API SL petrol car oil rating meaning if you ignore the label it’s a very good part synthetic option. And meets the specific Ferrari viscosity from 1973. Being a part synthetic means it will offer some of the benefits of a full synthetic, but with some of the features of a mineral ( cost )




The last option(s) is a 20W-50. We have 2 available, a basic Classic XL 20W-50 mineral oil available from Castrol Classic oils ( 01954 231668 ) and is a low detergent mineral oil. The other, again in the bike arena is the Castrol Power 1 4T 20W-50. Again a mineral oil, but with higher performance than the classic oil – and also quite suitable for cars of your pedigree and in my opinion a better bet than the Classic if you have a preference for a 20W-50

 

Here, where the diesel is everywhere, we use Chevron Delo 400. Full of ZDDP.

Spoke to the local Chevron Tech. and he said: great and cheap!

Regards, Alberto

 

The Rotella T 5/40 you mention is really outstanding stuff. The base oil is a group 3 hydrocracked slack wax so it's sort of a quasi group IV base. This base is indeed the same base oil used in Shell Helix, but the additive pack is of course different. I would only use this stuff in non-cat cars due to its additives though.


That all said, I believe in 2013 it was either GM themselves or some other firm that tested some 60+ oils in flat-tappet engines with really stiff valve springs in attempt to review the significance of ZDDP in oil to review just how necessary it objectively is. In short, their review yielded that ZDDP argument is largely a myth and actually showed oils with very high levels of ZDDP to in fact do more harm then good. Moderate levels found in Mobil 1 or specifically Pennzoil Ultra synthetic 5/40 (currently Ferrari, Porsche, Mercedes approved) tested extremely well. Shell Rotella T 5/40 was not tested, sadly, as I really like that juice. Mobil 1 actually has a flat tappet engine dyno which they use for torture tests specifically for flat tappet cam engines.

Ferrari, Porsche, and most engines with direct camshaft actuating cams do not run very high valve spring seat nor open pressures making the ZDDP oil issue even less applicable to these engines. It's the big American engines running 250lbs of seat pressure on mechanical lifters that see the real wear for obvious reasons. For comparison, Ferrari and Porsche run around 70-90lbs of valve seat pressure with their 2v engines and even less with the smaller 4v and 5v engines.

For me, and your results may vary (disclaimer), I don't get too caught up in ZDDP any longer and just run a top quality synthetic of appropriate weight in the modern stuff or quality conventional oil of appropriate weight such as Pennzoil, Kendall GT1, Chevron Delo 400 etc, changed often, in the 2v cars.