I only used it once Mick, I bought a K4 and did it up, then sold it to a British backpacker who wanted to ride around Australia. He wanted me to get a roadworthy certificate for the transfer of rego and get it serviced at the same time. The shop that did the work only used Pennzoil, and I don't know what grade they used, but it smoked like a bastard.
The poor bugger who bought it rode it to Sydney and got booked by the cops for "excessive smoke" so the buyer rang me and I suggested that he dump the oil out and refill it with penrite 20W 50 and he did, and hey presto! No more smoke. I haven't used it myself, and I've got no idea what grade it was, but it was thin.............
I throw just about anything in my bike, any cheapo supermarket oil is much better than the stuff available when my bikes were new, so I know I'm not doing them any harm. Of course I run an oil cooler on them too, but don't tell Lloyd, or this will turn into another war of words...........
