In regards to oil viscocities, part of the reason for all the different weights of oil is simply for climate and wear issues. Why would you use 20w-50 in a new engine
? Remember, heavier oils have more difficulty flowing through smaller and tighter clearance areas (I.E. new or rebuilt engines) which may result as higher oil pressure readings but could actually be lacking lubrication since it is the resistance to flow that creates the oil pressure reading
. Heck for that matter the NASCAR boys run about 10 PSI per 1000 rpm's
. too high of oil pressure is actually not good since it can wash out bearing surfaces and has even been known to cause a bearing to spin in its bore. Even my new Chevy Tahoe calls for 10w-30 from the factory. Even new Hondas run 5w-30
. I run 10w-40 in my carbed 22R right now and I'm using a TG8 Fram filter which is the larger Ford filter. (the only Ford related part on my truck BTW
) I do use 20w-50 in my chevy truck which has well over 200k on the engine and it runs great. It's OK to switch to heavier weight oils as the engine wears and gets older or if you change climatic regions for use.
Get over the "heavier is better" idea cause it's not doing your engine any favors. Also proper cam break-in procedures are super important when you run an engine for the first time. About 2000-2500 rpm for about 15-20 minutes the first time you fire it up (upon verification of oil pressure of course) should do the trick. This procedure will surface harden the cam lobes to prevent flattening in the near future. Hope this helps!
