Originally Posted By: FowVay
For the ALH TDI engine I'd not use a low-SAPS oil. These engines have nothing special that requires any oil other than the VW 505.00 requirement. They performed perfectly and for many hundreds of thousands of miles on Rotella-T 5W-40, Delvac-1 5W-40, Mobil 1 Truck and SUV 5W-40, etc. VW isued a service bulletin back in 2001 specifying the 5W-40 viscosity in synthetic formula only.
If you're set on servicing with Amsoil then stick with the original European 5W-40. There is no benefit to using the low-SAPS oils. They're designed for vehicles with DPF's (diesel particulate filters) in the exhaust. The ALH TDI isn't equipped with such a device and therefore you're better off using the oils with the higher TBN ratings.
When I had my 2003 ALH TDI, I used Rotella T-6 5W-50. Good stuff.
Originally Posted By: crazyman
AS for a PD engine, dont really know diesels that much. when i look up the specs for the engine it calls for 505.00. now the original and the newer 5w40 both spec 505, so it should be ok to use the newer one. am i right ???
For the PD engine, there are two schools of thought, follow the OE spec, or go off spec, I believe it was to a CJ-4 or CI-4 oils. These engines experience rapid cam lobe wear. Apparently either by aggressive settings or bad design or both. The off-spec oil seemed to reduce the wear rate, but not eliminate it. Once the cam lobes need replacement, the wisdom is to go to an aftermarket one that was engineered to address the problems of the OE one. Of course going off-spec would be a warranty concern, but out of warranty (as I believe by now, all North American PDs probably are), choose your oil based on common sense.