I've graphed these points and it seems like cSt = 3.5 x W I only consider cSt at 40 degrees C because it is for a fork oil application and it should not heat up too much unlike the engine. I first need to convert the W oil viscosity (5W, 7W, 10W.) to the cSt unit, which is standardized.įor the Bel-Ray High Performance Fork Oil which I wanted to use, here are the numbers Initially, I thought the final viscosity would be the arithmetic average of the W viscosities, but it doesn't work that way. Also this oil works for single viscosity oil (such as 10W), not engine oil such as 10W40 mixed with 15W50. If someone thinks I am terribly wrong, please let me know :)Īpparently.yes oil can be mixed, BUT : only the same brand and type of oil, preferably purchased at the same time to make sure the batches are close in composition too. I'm going to show you how I sorted this out. what if I don't want/can't use the BMW oil ? Can I mix other oils to get the right viscosity ? That exotic 11.5W oil seems to be a marketing technique to lock people into buying BMW fork oil.
