bosch makes a very good filter that is all but indistinguishable from the m1 filter and is half the price. i use both. even with m1 filters, it's still cheaper than a tear-down. m1 filters are only at autozone, but bosch are available at most import shops and many chain stores. i've been running 0w-30 for about 2yrs with no trouble (ok one pesky oil leak, but that's not the oil's fault). i run it year round but we only get a high of 90 maybe three days a year up here.

97Rodeo Rancho9ks/Aisins/3.2L SOHC/M1 only
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Proper Prior Planning Prevents P*ss-Poor Performance--Maj. R.T.Spooner USMC(Ret.)