What is the best product to use when my engine hasn’t been serviced in a while? October 23, 2012 Solutions Central › What is the best product to use when my engine hasn’t been serviced in a while? 0 Vote Up Vote Down BPfan Staff asked 12 years ago I haven’t done much maintenance on my car, and now the engine is sounding rough. Any recommendations on the best Berryman product to use in this situation? And what is HEST? 1 Answers 0 Vote Up Vote Down chemtooler Staff answered 12 years ago You may want to consider the B-12 Chemtool Total Fuel System Clean-Up product. It’s made for cars that haven’t been maintained as much as they should. Please login or Register to submit your answer Username or Email Address Password Remember Me