Hi all, bought a 2005 GX470 a few weeks back in Armenia. After closer inspection (after purchase), I noticed that the inside of my oil cap had moderate amount of sludge inside. I haven't popped open the valve covers or oil pan to verify how much sludge I'm dealing with here but are there any recommendations on an engine flush with a reputable product?

Thank you in advance.

 

If you have good oil pressure just use a semi synthetic oil with better cleaning detergents for high mileage engines.

I have considered dropping the oil pan to see if the screen on the oil pumps pickup is getting any buildup. Which I think is where oil starvation begins.

Flushing can remove good buildup that is wanted at startup. I wouldn't start a problem by removing that good varnish, Just use a good detergent oil and watch the oil pressure.

 

Will consider that. Thank you.

 

^^ solid advice, MDSteamer.

 

Moisture collects in the cap and causes this, don't judge the engine based only on what you see under the cap. Not a fan of any engine flush products.

 

First verify there's actual sludge. Remove the driver's side valve cover. The aluminum should be a nice golden color, with some areas dark gold where the PCV valve is (normal level of varnish).

This is not a GX engine, but a sample of what it could be with sludge..
Imgur Link

If you have sludge ...
If the area under the valve cover is truly horrible, you will need to scrape + vacuum out what you can from both valve covers and the oil pan first with a plastic spatula/tool. Then replace the covers and oil filter.

Then do about 3 repeated cycles of:
1. Add half a can of Marvel Mystery Oil or other solvent intended for oil (Seafoam can't be used in oil)
2. Add oil to bring it up to normal level.
3. Drive in town, with lots of start/stop traffic but little idling, so that the oil pressure fluctuates. Do this for 30 miles/50 kilometers.
4. Drain the oil, replace the filter. Go to step 1.
After the 3rd time, reinspect the valve cover area to see what improvement there is.
If it's looking good, refill with oil and enjoy the GX. Otherwise, repeat some more times.

The idea is to flush the sludge out into the suspension in the oil, with larger chunks in the filter, and then change the oil + filter often enough so that the engine doesn't get starved for oil.

Note that this is a "best effort" - you might still end up replacing the engine because it was damaged by the sludge.

Chip H.

 

LuxDreamer,I am a Dealer for Amsoil and always reccommend an engine flush on all vehicles bought used,especially if the maintenanance history is now well known.Below is a link to the product.If you have any questions,let me know.

https://www.amsoil.com/p/engine-and-...-EA?zo=5544139


https://toptiersynthetics.myamsoil.com/

 

I have used LiquiMoly #2037 (flush). My engine though was fairly clean to start with.
Sludge is not ez to get out.

Did previous owner(s) not use full synthetic oil?

You should also look behind the throttle body into the intake, is there a lake of oil laying in there? If so then the intake runners from intake down into the heads also probably have sludge in/on them.

If it's a ton of sludge then might need to yank the heads off, then clean everything you took off really well, then put it back.