I am the proud owner of a '96 Chevrolet Caprice with GM's LT1 5.7L engine. It has the B4U SPID code, which means among other things that it has the heavy-duty cooling package for both engine and transmission lubricants. It was *not* a police cruiser, and Carfax verifies one-owner private vehicle status. I bought it used with approximately 67K on the clock and it is now approaching 3,000 miles on the oil the OldsBuickPontiac dealer put in it when they got it. The salesman claims that he got he it from a guy who took immaculate care of it and had all the receipts for all the service items... but they all say that. I love this car. What oil and filter combo would you reccomend using in the crankcase? I'm planning on running the next oil to 3K, then sampling it and making judgements on interval from there. I'd sample my current oil, but I don't know what the **** is in there, and I just got the car back from being in an accident that broke the air cleaner. The vehicle was operated for about 60 seconds with the air cleaner cracked, and I worry that might contaminate the sample in my current crankcase fill. I'm located near Akron, Ohio. The record low for this city is -24 Fahrenheit but per my wife we rarely see below -10 Fahrenheit. The oil that pops to mind is M1 5W30, given the ready availability and association with the Corvette's LT1, but all suggestions will be entertained.