Motor flush

[mindbomb]

Thinking of doing a motor flush on my 03' KJ the next time I do oil change which is soon.
Hopefully will restore some lost power but mostly hoping that'll improve the subpar gas mileage I'm getting.

Pro / cons?
Recommended material?
(Considering Gunk MF3)



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[dude1116]

Never found a need. So long as the oil is changed in proper intervals, your motor will have little to no gunk in it. Feel as though it can do more damage to seals than anything else.

 

[rjkj2005]

Find someone that deals in BG products. They make a great product. A lot of factory dealerships use and sale their products.

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[JasonJ]

Lost engine power is rarely the result of the lubrication system being gunked up. If it's gunked up that bad, you've got more serious problems, and consider that any debris or sludge that thick or substantial, is likely just going to get washed down into the oil pan at best, and into the oil pan and block your oil pickup tube at worst. Are you planning on dropping the oil pan to clean that out too?

If I had an engine with low power, I'd be doing a compression test on the cylinders first.

 

[mindbomb]

Not sure about lost power (no other reference KJ to try) but very sure about low gas mileage I should be getting more


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[teeje]

Don't flush it. Any "sludge" that's sealing a gasket will cause leaks.


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[renegade 04]

If you have bad gas mileage try changing the spark plugs.

 

[BorincanoKJ]

if you some one wanted to change from regular to synthetic oil. It is or is not recommended to use additive for motor flush?

Thank you for the suggestions.

 

[HoosierJeeper]

I would probably say no to the additive. I think just switching would be enough of a change, I think with these things gradual changes are the best.

Although if you have over 50-70k miles, I would just stick with what you've been using so far and change it often. Putting synthetic in a 150k mile engine won't make it a new engine and if it's made it that far, you've done something right.

 

[teeje]

I would probably say no to the additive. I think just switching would be enough of a change, I think with these things gradual changes are the best.

Although if you have over 50-70k miles, I would just stick with what you've been using so far and change it often. Putting synthetic in a 150k mile engine won't make it a new engine and if it's made it that far, you've done something right.

On top of that, the synthetic will truly clean up the "gunk" and cause it to block and pickup tune in the pan. I have a new engine and I've put synthetic in it ever since I had it put in. Always stick with same brand of oil and type IMO

 

[CactusJacked]

Thinking of doing a motor flush on my 03' KJ the next time I do oil change which is soon.
Hopefully will restore some lost power but mostly hoping that'll improve the subpar gas mileage I'm getting.

Pro / cons?
Recommended material?
(Considering Gunk MF3)

A definite big NOPE on using the flush, I see nothing good that can come from running "watered down" oil through the engine. If you're worried that you may have sludge or gunk inside the engine, switch over to full synthetic (Mobil 1 is my favorite). It will clean out the engine gradually over time, doing no harm. You don't want to loosen a lot of crap all of a sudden with a flush, this is assuming you even have any.
Also, do the math; synthetic is a superior lubricant and can go twice as many miles as conventional oil, so doing half as many oil changes means synthetic is actually cheaper to use than conventional oil is, even though it initially costs more. Why some people still debate that synthetic isn't the way to go is beyond me, guess they flunked common sense and math class in school.
And no, you're not going to magically gain back some lost power with an oil flush. What can happen (has for me) is synthetic can clean out sludge and varnish from the lifters and quiet them back down. Notice I said can/has, not will.

 

[Conundrum2006]

Don't do it! If there is gunk/crud your more likely to break it free and clog the pickup tube. Although mine was a case of very bad neglect by the previous owner.

Pull the baffling out of the oil filler neck and see what it looks like. If it's really thick with crud a flush will hurt more than help.
I'd recommend synthetic oil and oils with detergents over a flush any day of the week.

If you do flush get a shop with the proper equipment like those who specialize in BG flushes.

If you do have gunk and it clogs the pickup tube it will either kill the engine or require dropping the pan and a new pick tube. A huge job in the KJ.


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[BorincanoKJ]

Ok! I would stick what i been using so far which is regular oil. My engine mile is 160k I will be doing as always.

Thanks Hoosier.

 

[mindbomb]

Ok I will pass on the flush and return the additive to the shop thanks for the tips! I bought 5W-30 synthetic oil Mobil 1 high mileage and KN oil filter.

Spark plugs were replaced less than 10k miles ago. What other regular maintenance issues may cause bad gas mileage?
Clean throttle head? PCV valve?

 

[Conundrum2006]

Pcv valve is right up front and sort of easy to get to. Although the ac lines gave me grief but that's a slightly different to set up too.

How bad is the gas milage? Even going from a gunked up motor to clean low milage motor didn't change my mpg drastically. And that's with full time 4x4.
Got to be something else affecting this. (On the old 4.0 Cherokees I'd be thinking o2 sensors. Or something like that)



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[mindbomb]

Getting 14mpg combined with the 03 KJ, drives fine but too thirsty compared to other people's stats.

 

[JasonJ]

Getting 14mpg combined with the 03 KJ, drives fine but too thirsty compared to other people's stats.

What is your driving style like (and be HONEST)? Everyone always says they drive normal... or "not too aggressive".. they're fibbing. lol.

How high does the engine rev while you accelerate normally? Are you a half throttle at every green light kinda guy?

I drive like an old man who's pissed off that his paper boy was 3 minutes late that morning... people pass me because I don't accelerate as fast as they do. I get to speed, I just aint in a hurry to do it (I still accelerate quickly enough to not slow down traffic or cause safety issues). My engine rarely goes past 3,000rpm on a normal city/rural highway acceleration. Expressway, different story, get your **** up to speed!

How about your differential fluids? Changing mine seemed to help my mpg. New trans fluid and filter recently, like in the past 30-50k miles? If the trans is slipping slightly, or not applying all the power to the axles, the engine is going to have to work harder for the same amount of acceleration.

That being said, I avg 18.6-19.7mpg city/55mph highway. Routinely see 20-21.5mpg at 70mph on the expressway. Higher when I'm cruising along on a 55mph rural highway. I use cruise control when possible, and coast to stop lights (even yellow ones) when appropriate.

Also check and maintain your tire pressures.. even just 2psi off is enough to make a difference.

 

[TheBlueKJ]

I swapped to mobil 1 synthetic at 120k. It definitely cleaned out the motor as I could see a difference in the oil color over the past few oil changes.

Only drawback was it cleaned out the gunk sealing up some leaks. I see this as a good thing though since now that I've fixed them all I have no leaks at all hidden or otherwise


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[uss2defiant]

Getting 14mpg combined with the 03 KJ, drives fine but too thirsty compared to other people's stats.

I dont think the EVIC is accurate at all.

 

[HoosierJeeper]

Ok! I would stick what i been using so far which is regular oil. My engine mile is 160k I will be doing as always.

Thanks Hoosier.

I'm at roughly the same mileage as you, 152k, and at about 145k I switched to Valvoline High Mileage oil. Helps clean some stuff out, get slightly better MPG with it maybe and it seems a bit happier. It's a semi synthetic. Could be worth a shot if you want to switch it up.