quote:Most EP additves today (since about 1995) include corrosion inhibitors and metal deactivators so the copper alloy corrosion scare is largely a thing of the past. Modern "dual-rated" GL4/GL5 lubes for MT's are completely safe. I know ours are after 5 years+ of testing in all kinds of manual transmissions.
the difference is a GL-4 will take a treat of 2%wt and a GL-5 will be a treat of 7%. same additive just more so normally a GL-5 will work fine unless the higher additive causes brass corrosion then a lower GL-4 will be better
quote:Because the dealer markup for a cheap mineral oil isn't justified. Plus, to increase profit margins, some dealers will use non-OEM fluids from their 'bulk oil distributor' instead of the company branded products. Most "boutique" oils cost the same and perform better!
Originally posted by Leo: Why not just use OEM fluid if its difficult to find?