Ive heard its really good stuff to use to clear out alot of the sludge that sits inside of an engine. I am thinking of using it later this week when i go to do an oil change. Any thoughts on this? Good idea or bad? The car also doesn't leak oil..so that may or may not be a problem.
Has 154,500 on the clock too.

I have used Gunk engine flush before, It worked great. The oil was alot blacker after running the flush so it must have cleaned some stuff outta the engine.
But I also heard of people using engine flush and messing things up. Sometimes that slug in there helps seal things.

I've used it in ALL my some 20 cars! Never had a problem.....Just remember though to get it ALL OUT afterwards though. I recommend a very long drain. Then flush some clean oil though it & let it drain out too.

I was reading one guys review of the stuff and it made sense. Your oil filter has a bypass valve that'll let oil go around the filter if it gets too clogged. A decent idea, bad oil is better than no oil. But if you do it just prior to your regular oil changes (or especially if you're late) your oil filter is already filling up, then you flood it with handfulls of sludge that the product broke loose and you may trigger that bypass valve to open. The guy actually renamed it "Insta-Rod Knock" and with seemingly good reason. When I took my engine apart at about (if I remember right) 90k+ it had sludge that could fill a 7-11 Big Gulp. If even half of that broke loose I'll bet it'll clog the filter and the bypass valve will let the rest through and straight to my bearings. I have used it once before but I was really worried about it, even before hearing about this guys testimony. While I was in line buying it some old guy infront of me was telling me about his stories of it and how you should "really be careful" and the he would never use it again. If I was to ever do it again I'd put a little extra $ in the oil change fund and drain all the oil, refill it with cheap oil + cleaner + a new filter. Run it for the designated amount of time then do my normal oil change. It may seem like overkill to some people but in my mind its better than being "that one guy."

i dont know if i would use it in a badlt sludged engine. in a well maintained engine i dont think it hurt to give it a little extra cleaning at oil change. i put in 1/2 quart of gunk twice a year. a long time ago i did have gunk flush reveal a small rust hole in the oil pan. 2 hours before some guy was coming over to most likely buy the car ! lol

I bought my car with 111,000 miles. I changed the oil the first couple of times with regular oil, then the next couple were with mobil 1, and the latest one with amsoil. Each time I let the car drain for about an hour. I put the new oil in and drive around for a day. I check it again, and it is as black as my tires. Would you not recommend an engine flush if it'* this dirty?

You may want to replace your PCV valve if you haven't already.

I had not even thought of that. Thanx. I'll have to pick one up. It probably has never been replaced anyway and I think they're only a couple of bucks.

I have never heard anything good about that stuff. This is the first time I heard of someone liking it. I can understand the insta-rod knock theory.You can remove thuosands of miles of sludge in one oil change! If the motor is that bad, it probably doesn't have much longer to go. This should never happen with regular oil changing espically with synthetic oil. :?

What you have to remember here is that there IS a difference of WHEN it'* safe & not safe for an engine....It'* SAFE if down on a regular basis since the car was new. It'* UNSAFE if done on an engine that has very high miles on it! I've ran synthetic oils in ALL my cars & do do a "Engine Flush" to them every Spring. With synthetic oil, I change it every 7,000 Kms instead of the "dino" 5,000 kms.