When to switch.....

Central Ohio
viscosities? Haven't paid much attention to this before, but I noticed the M1 5w-30 SS has the "Newer Vehicle Formula" label on the bottle. At what point should one change to an oil with a heavier viscosity or a "older vehicle" formula? Currently have 80K miles on a 1999 Taurus (3L, 12 valve). Its lived on a diet of M1 5W-30 since I have owned it at 19K miles. It uses about 1 pint in 4K miles, and runs and sounds like new. Any ideas? CC3


Staff member
Oakville, Ontario
One way to figure this out would be if you've been doing oil analysis all along and you notice the wear has been steadily increasing, then you could try going with an oil that is slightly thicker to see if wear comes down. Try going with an oil whose viscosity spec at 100C is 1cst higher for instance. Even if you haven't been doing oil analysis all along though, you could simply do one right now and see if your wear numbers look reasonable or not, and if you're not happy with the results, then try out something thicker to see if it helps.