1995 GMC Jimmy Remove Carbon - Clean Engine

So what exactly are you looking to do? Are you looking for and additive to put in the fuel and oil to protect and clean or? You mention removing the valve covers but I must ask why? Get back to me so I can better assist you.

Dear RACEFAN966 ? ,

My Jimmy has 221 K miles and presently is running pretty good. I am finding that the spark plugs are
accumulating much carbon build up, oil fouled, and bridged ash deposits. I have changed the spark plugs
3 times in the past 6 month's. Due to this accumulation. Presently, I am using the stock AC spark plug, prior I was using Bosch.
The Bosch did not seem to have as much of the previous mentioned deposits, but were reading as if they were the incorrect heat range - the reason I went to the stock spark plug. Would you suggest going back to Bosch ? (maybe I can be more critical in the heat range plug partnumber).
I performed a compression test and all cylinders read above average psi and all cylinders were very close in readings with each other ! Very Good for the age of the Engine.
Primarily, I would be looking to Clean and De- Carbon the Engine Components which I can get to with the Engine still in working order. Back to the topic of Valve Covers - since I have owned the vehicle since 2003 a valve cover has never been opened. I am not sure about previous owner, and possibly, the valve covers have never been opened.
I understand from readings that this Engine and All engines of this mileage will develop more Oil usage due to Piston Ring Wear and Valve Guide leakage - slop. Yes, I am using more Oil these days, not excessive, just more. Gas Mileage is close to the original stock specification. The Engine still has alot of power and I can cruise nicely on the Highway....
Can I open the valve covers and clean the upper parts of valve train and would this be a benefit ?
Can I add a Engine Flush to the Engine while it is intact and let it sit in the Engine to soak a day or two
and then flush through similar to an oil change ?
What are your suggestions of an engine with this mileage ?
Thank You

Thanks for any suggestions.

I would not suggest an engine flush as this may cause more problems then it helps as the mileage on the engine is very high. I wouldn't pull the valve cover to do any cleaning there either as that may make the valve guide seals even worse then they are too. So with that I would get the Z-MAX for the engine and gas it comes in a pack use it follow the instructions on it and thats it. As for the spark plugs if you are seeing signs of oil on the plugs I would step up one heat range and keep in mind that you will have one of two choices in the future replace the car or the engine. I hope this helps and answers you question if not please just ask and I will try to better explain ok. Thanks.