auto-tune-up-and-repair.com, Mega Power Vehicle Additives, George Christ Destroyed truck engine, will not refund San Marcos, Texas Nationwide!!. Engine noise in truck. Purchased product for $90 which had a money back guarantee if not satisfied. Product not only did not work but after taking truck to service dept of auto dealer, had to replace timing chains. After replaced, new noise appeared from right side lifters. Each time something was repaired or replaced, new problems appeared. Mechanic thinks it was the additives which caused all these additional products. Company refuses to refund $90. This product cost me $90 plus the cost of 4 oil changes and replacement of the truck engine for $3500. Original truck engine that was replaced had 92,000 on it. Had to be replaced with a used engine with 122,000 miles on it.