Goodbye Crane Flat Tappet. I hardly knew ye.

Yep all flat tappet cams need a high zinc (ZDDP) oil to live long & prosper. There was a discussion of oil formulation recently on a vintage road racing mailing list I belong to (from various posts):
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Brad penn 20/50 synthetic blend PPM zinc 1500z PPM phos 1400P

Mobil 1 0/50 or 0/30 racing PPM zinc 1850z PPM phos 1750P

Mobil 1 v/twin 20/50 or 10/40 mc racing PPM zinc 1700z PPM phos 1600p
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We use VR1 20w/50 for our customers with older engines that do not want to use synthetic – I strongly recommend synthetics for everything and have been using them in race cars, rally cars, tow vehicles and everything else since around 1992 (included in that list is pre-war vehicles) While the VR1 does have a enough zinc in it to just be OK for flat tappet vehicles it makes it by the skin of its teeth – it is street legal and carries an SN rating – it is just a bit too high for extended use in that rating – which is why, though it is technically street legal, it comes with a warning that it “may not be suitable for extended use in cars with catalytic convertors – a few years ago it was classed as not street legal but they lowered the sulphated ash and zinc levels – and the sulphated ash is as important or perhaps a bit more than the zinc – zinc will not work with out the ash

We use Amsoil – they have 3 products that fit your needs – the highest zinc and ash is to be found in 2 of the products – 10/30 and 20w/50 Zrod oil and then they make a full line of races oils but they actually are a little less in the zinc and ash – modern race cars are not flat tappet – there are other reasons besides cat life to lower zinc and ash – Brad Penn has some – read the labels closely if you have sm or sn ratings you barely squeak by and it is other chemicals in the additive package you are now relying on – Castrol supposedly has one – 20w/50 synthetic – but I trust them anymore about as far as I can toss my Jag – they and their engineers left me hanging out to dry when this mess all started a few years back – we were a dealer and I was friendly with some guys in the R&D departments –

Just because an oil says it is high or has a high SAP rating does not mean it is high enough for you – Pull the data sheet and actually read each number– to be correct for older flat tappet the highest rating can be SJ or SL – if you have any ratings higher than that the SAP package has been changed to meet the API ratings and if you look at the data sheets you may find that other numbers went up but the two you are most interested went down
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I now use Amsoil DOMINATOR® 15W-50 Racing Oil. Lowered my oil temps about 20 deg. F. and it also is doing a better job of protecting my gearbox which unfortunately shares the oil with the engine (Mini). I have used Valvoline and Alisyn in the past and switched to Amsoil. Very pleased.
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End of quoted material.

Me? I use roller cams but also run Brad Penn 20w50 Racing Oil. Roller cams are more expensive but a are good for more than just avoiding lifter ware. They also free up power and improve milage by reducing the internal friction of the engine and help make more power by permitting faster valve opening and closing events. This is why a roller cam that has the same basic specs as a flat tappet will usually beat the flatty by 25-30 HP. Yep, they cost more, they also make more power.

Dave