JC, I'm no oil guru, but I'd be guessing at a cam heat treatment problem. Have you seen this on anything newer ?Quote:
Originally Posted by justinc
Are the rockers rollerised ?
The other thing is that M1 5w-30 doesn't have the EP/AW additive package of say, Delvac 1 or I'm guessing Penrite HPRD5. It is a petrol engine oil.
Mobil 1 5w-30 may be synthetic, (and that's debatable after Hurricane Katrina) but it's definitely not the best oil going around from what I've heard. It's also formulated around North American engine designs and is known as an energy efficient oil, ie. low drag. It also has a relatively low HTHS figure (high temperature high shear) and is a relatively thin at around 10cSt@100*C, so it only just makes the xw-30 grade. I'm guessing that M1 0w-40 would be more suitable as it is a dedicated Euro engine oil with lots of VW Tdi's running around Europe using it. While it does have a bit of a reputation for shearing (thinning) due to the wide viscosity spread, it is the OE oil in a few Euro makes, and a bloke I have a great deal of time for when it comes to lubrication matters uses it in his Merc, but he does use Delvac 1 in all his other petrol vehicles, including his Porsche, as he reckons it's the best all round oil he's ever tested and used, and I'd reckon he's studied more used oil analysis reports than I've had hot dinners. ;)
I've also heard of some of these problems occurring in other engines with some of the newer oils that meet SL/SM spec, particularly old style flat tappet V8's as the anti scuff/anti wear additives used in very old oils like ZDDP can't be used in new vehicles as it poisons the cat, and while newer additives can take their place adequately they aren't being used to the same % as the valve train loads aren't as high on newer DOHC engine designs.
Japanese diesels had a similar problem back when the API announced the CG-4 diesel spec and the fix thereafter was a healthy dose of calcium, IIRC above 3000ppm which acts as an anti-scuff, as well as having detergent/dispersant properties.
To this day, all Japanese diesels pretty much sold in Australia will have their warranty void if anything other than an API CF-4 oil is used, yet the spec is near twenty years old :eek:
Most all Japanese diesel specific oils have the 3000ppm + calcium add package just to comply, even though there are other ways to build the oil successfully.
Even oils like Delavc MX, MX-Super, 1 and Delo 400 which have excellent AW/EP packages aren't acceptable to the Australian arms of the Japanese manufacturers as while they meet CF-4, they also exceed it by meeting all the current specs. :rolleyes:
