Originally Posted by willk
.....On a funny note - a boat showed up at a particular yard recently with one leg full of ATF and the other full of chip oil. No idea if they were actually run with it of if it was for the antioxidising properties / flavour
And it likely did no harm. Maybe depends on the number of fish it fried in a previous life but some seed oils have very good film strength - remember Castrol R? a castor based product. ATF is a very good lubricant too and many auto transmissions are filled for life....and that's the problem with oil recommendations, most modern lubricants are pretty good so how do you know what is good and what is better unless you run two similar engines under similar circumstances for an extended period until one of them suffers an lubrication related failure? Tricky.
So, for me, with engine oils, if it comes out after 4k miles looking like gnats' pish or unusually dark and smelling burnt, and some do!, that particular oil type doesn't get used again. If google is your freind, a good search will reveal some comparisons of the loss of viscosity of popular brands and grades of oil. Some of the big players are not necessarily the best - but mantaining viscosity, whilst important, is not the only consideration.
With gear oil, if it comes out particularly dark or looking like metal flake paint it doesn't get used again.
For the record, I buy my lubricants in bulk because I have four diesel engines, umpteen axles and a couple of marine lower units to service and I can standardise on oil, my supplier is a Fuchs agent and they are a word player in the field of lubrication so I buy that. It seems fine and one of my vehicles is now in its thirteenth year and mechanically sounds as good as it did when new. 4K oil changes though.
My final little story... my partner has a Can-am Spyder (look it up) and was supplied with a Can-am service kit of oil and filter when she bought it. The first oil change was done at very few miles and the original fill oil came out like dilute pish, the service kit was used and at 3k it too came out like pish. The Spyder requires a fairly high spec oil so where to buy?... The local Spar grocer had it in stock - yeh, really! and cheap too. At oil change time it came out looking just as it did when it went in but a little darker - more amber nectar than golden syrup. Needless to say, we went back and bought quite a few litres while it was still available - good thinking as it turns out because it's no longer available there. But, long term....I'll let you know in a few years.
In my motorbike I use 20-50 dino oil...but that's another story.