[Mgs] oil

[PaulHunt73]

>From my reading of spec sheets of oil available to me in the UK modern oils (including for Diesel) have had their ZDDP reduced over time as much for environmental reasons as for damage to catalysts, but then so have some 'classic' 20W/50 formulations.  ZDDP content is what the manufacturer chooses to put in, so you can't say that any weight or API rating is automatically going to have a particular content.  For example a few years ago Castrol XL 20W/50 SE was showing 800ppm, whereas GTX 15W/40 SL showed 1035, and GTX Diesel 15W/40 1200.  For classics they recommended their Syntec 20W/50 at 1200, whereas claims elsewhere said that their GTX 20W/50 would always be 1300-140ppm.  Mobil 1 Fuel Economy 0W/30 quoted 1000 whereas their Super 3000 Formula R 5W/30 showed 500.  I've also seen a letter purporting to be a letter from Royal Purple stating that RP XPR 10W40 has over 1500-1600 ppm of ZDDP and "we could take all of the ZDDP out of our engine oils and still have 4 times the wear resistance of even the VR-1 oil due to our Synerlec additive technology".

At the moment over here the highest concentration seems to be Classic Oils Heritage 20W/50 at 1300ppm https://www.classic-oils.net/Classic-Oils-Heritage-20W50

A friend has personal experience of a new cam and tappets being wrecked in just 20k on a semi-synthetic 15W/40 SL, but from other things I have read really old classifications such as SB never had that much to begin with, and engines didn't suffer damage.  So I suspect the problem with rebuilt engines is as much to do with poorer quality components these days as anything else.

But as I say that's the situation over here, and as someone else said this discussion could go on for ever.

PaulH.
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