I, too, had shared this concern, until I read somewhere that the higher number is the "real" viscosity, and the lower number is how the oil reacts in cold temperatures. That is, a 0W40 oil is a 40 wt. oil, that maintains a viscosity similar to a 0 wt. oil at 0 degrees C., or something like that -- it doesn't get as "thick" as a 40 wt. oil would at that temp., it's as "thick" as a 0 wt. oil would be at that temp.
Please correct if I'm wrong --- On 9/30/06, Peter Frederick <[EMAIL PROTECTED]> wrote:
0 weight oils are too thin, in my humble opinion, for any diesel. Too much pressure on the journal on the compression stroke, not enough film strength, even for a synthetic like Mobil 1 The difference between dino and synthetics is huge, the difference in cold viscosity of synthetics is fairly small. I believe the 0 weight oils are intended to give small gasoline engines a bit better milage from lower oil pump resistance, not something I'd like to try in a diesel! Just my opinion. I tend to use 5W40 or 5W50 Truck and SUV or 15W50 Mobil 1 in the summer and 5W40 in the winter, but if I need to change the oil and can only find 15W50 in the winter, I use it. Hard starts are usually not helped by lower viscosity oil unless you have fairly high viscosity dino in the crankcase -- I've seen an engine that simple would not crank at all in the winter with 50 wt in there to hide a bad bearing.... Peter
-- OK Don, KD5NRO Norman, OK "The Americans will always do the right thing... after they've exhausted all the alternatives." Sir Winston Churchill '90 300D, '87 300SDL, '81 240D, '78 450SLC, '97 Ply Grand Voyager
