Engine Power Flush at Jiffy Lube

[Bhatti, Mohammed]

Anyone come across this at they're local Jiffy Lubes?  They claim that upto
a half quart of sludge, contaminated oil etc remain in your engine after an
oil change and this stuff mixes in with the new oil they put in.  They offer
this service called EnviroLution that power flushes this stuff out and is
recommended every 12000 miles at a cost of $80.  Claim that it prolongs
engine life, fuel economy etc.  Is this a valuable service or just a rip
off?

mkb
88 80q