Yesterday, I noticed the Castrol GTX HM at a Checker/Kragen store while I was shopping for a HM oil out of the group of heavy 10W-30's, (Chevron, Havoline, Citgo, Pennzoil) that run about 83 cSt @ 40C.
These heavier HM oils noticeably reduce the noise at startup for my Silverado 5.3 Vortec engine.
Chevron was $1.99/qt & Havoline was $2.19 even though the product data sheets list identical numbers, with the exception of TBN, 7.9 for Chevron & 8.0 for Havoline. Go figure!
We have had good luck with the Castrol GTX HM. As for fixing leaks, the MaxLife is the only one that has lived up to that repair. But, I see the Castrol GTX HM at most every chain auto parts store in this area. Are there any other chain/discount stores that may stock it? Check around...in fact the auto parts stores have been running coupons and it is actually cheaper to get it at the parts stores than at Walmart. That is nice you are supporting other business. But we have seen great oil pressures, ceased oil usage and blow-by, great engine sound. Well, I think it's a great choice and good luck in your search!!!