I'm currently in my rinse phase. Should i do a second treatment for a vehicle that only has 23k miles but has a long history of sludge issues (Toyota)? Would a second application be overkill? Should I do a yearly clean and rinse? Thanks.
More info is probably needed here. If you have a sludge-prone toyota engine BUT it only has 23k miles on it AND the oil changes have been kept up properly, I doubt a second app is needed.
A yearly app is a good idea and will keep you cleaned, though some will say to just go on the maintenance plan instead (see instructions).
My personal opinion would be to just run the maintenance dose with each oil change and don't shoot for any long oil change intervals, if it is in fact a sludge proned motor.
