I want to switch to Schaeffers S7000 in my vehicles. They are 97 Ford F150 4.6L 99K always on Penz dino. 99 Honda Civic 1.6L 67K always Penz dino. 96 Ford F150 4.9L inline 6 just bought but has Valvoline change interval sticker on windshield. What is the best cost effective way to clean these engines before putting in the Schaeffers? I use Motorcraft, WIX and Baldwin filters. Live in Missouri with a mix of hiway & city driving, no racing & pretty clean air conditions. Temps range 100 F in summer to 0 F in winter. Mostly temps from 10-90 F normally. I want to choose 1 wt for all the vehicles that will handle these conditions as well as the tighter tolerances of my 97&99 vehicles. What weight S7000 would you recomend? Would 10-30 or 15-40 be appropriate? Also where would I find a dealer in my area, Springfield,Mo 65804? Thanks, Gary