Realize that the number before the W (Winter) and the numbers with no W have no relationship to one another past that the higher the numbers the more viscous the oil. The values are arbitrarily assigned based on a flow rate when cold and when the oil is hot. So, for example, a 20W-20 oil would NOT be the same thickness at say 32F and 100F The 0,5,15,20 before the W are the viscosity at some cold temperature (I don't remember what the temp is, maybe 32F.?). The second number is then tested at whatever the specified temp is for that test.(seems like that is 100F.) A "straight" 50 weight is not a 50W-50. It is effectively a ?W-50 oil. It was either never tested or for some reason never given a W viscosity rating. So a straight 50 oil may be a blend of whatever oils were leftover that would net a 50 viscosity. It could also be oil specifically blended without any additional viscosity improvers or other unnecessary additives which is what most people are generally hoping for with these types of oils, but unless otherwise stated is not guaranteed . I made some edits to this post to try and make it cleared but I'm not sure I really did... Either way I'm going to leave this as-is and see what becomes of it.
Thank you Your explanation is about easiest Ive read. first # is the weight cold Second # is what it acts like.. I like this board.......
I would check the pump clearances first. If they are loose, try and correct them if possible, if not, get a new timing cover. Using thick oil for a loose pump is a band aid. Oil pressure is very important for these motors. If the motor was built with larger bearing clearances, thicker oil might be your only option if you don’t want to open up the motor. Rule of thumb is to use the thinnest oil that gets you satisfactory oil pressure. Using thicker oil just increases pumping losses and further heats the oil. Just my .02.
