A newbie here, so be gentle... I ask the following as someone who is, in his early 30s, now sort-of getting involved with cars; the mechanics, electronics, et al. are becoming a bit more interesting to me than they once were. I've always deferred to (and paid) my gear-head brother for help as I've had other interests. Lately, I've come to realize sometimes the best help is self help, or help from outside sources, so here I am. Anywho, enough about me... I have two Chevy Caprices I'm fixing up for relatives, running the same style standard small block 305, both with TBI, one an 89 Classic and the other the infamous 1991 Bathtub Model. Both have miles, the bathtub however runs much smoother and has maintenance records and all that, whereas the Classic was a teenager's car for awhile and suffered a few moments of over-exuberance and poor maintenance. Thanks to various rebates and sales over the course of the last couple of months, I've ended up with 2 5-qt jugs apiece of Pennzoil Platinum and Mobil 1 High Mileage oil (for under 2 bucks a quart after rebates - both are 10w-30, as it never gets below freezing nor above 90 around here). TO THE POINT: I'd like to keep the bathtub running the best (it occasionally has a start-up poof typical of an aging 305), and the engine seems the strongest in that car (the other car, at a minimum, will be getting valve stem seals and valve cover gaskets replaced before an oil change). In the opinion of people who seem to know, would it be better to put in the High Mileage oil into the car I'd like to keep running longest, or go with the newer Platinum oil (non high mileage) which seems to have better specs overall? I am leaning toward running the HM in the bathtub, just to help the seals which don't seem to need much help. Two variables: 1) I live in Oregon, home of 10% ethanol. As a sub-question, would one of these oils be "better" for use with such gasoline? 2) I do have a bottle of Schaeffer's Moly EP #132 at my disposal, if that would be of benefit to either car and/or oil. Thank you in advance!