Gnarly looking spark plugs. 8.1L 2500HD

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The mileage on these is unknown. My truck has approximately 150,000 miles. I owned it for 5 years but I only drive it 2k miles a year ish. The original owner was a older man and seemed rather meticulous.

I don't know what mileage these Autolight XP5245s went in at or if this is a correct plug.

I won't go off on my internet forum and tuning reading decision making but I put in TR55s gapped at .045 rather than factory .060.

The only modification to the truck aside from some exhaust is a 180 or 170° thermostat. Lowering the thermostat temp stops/reduces the oil vapor consumption issue the 8.1 has. And to me these plugs look like the truck consumes oil still but frankly I am hardly seeing any consumption. The only unusual circumstance prior to the plug change was I had this thing idling for probably an hour and a half in the hundred degree weather we had while I have someone sitting in it with the AC on so I could bleed the brakes.

Differences, starts a tad quicker, exhaust smells different, idle is smoother though I liked the way it ran with the old plugs. Mpg was 10-12 prior. Put NGK blue plug wires on it too.

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Parked at a random vacant house

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Nice truck.
Lowering the thermostat temp stops/reduces the oil vapor consumption issue the 8.1 has
Hmmmmm.....not so sure about that. It might be why your plugs look richly fouled. Not sure of the temp that the 8.1 leaves open loop and goes to closed loop, but 170 is likely not it. The engine might be sludged. Recommend HPL engine cleaner in 40grade.

A smaller gap should be more powerful, but will take more power at the coils. Sounds like the old owner was trying some old school tricks on a newer school truck.
 
The mileage on these is unknown. My truck has approximately 150,000 miles. I owned it for 5 years but I only drive it 2k miles a year ish. The original owner was a older man and seemed rather meticulous.

I don't know what mileage these Autolight XP5245s went in at or if this is a correct plug.

I won't go off on my internet forum and tuning reading decision making but I put in TR55s gapped at .045 rather than factory .060.

The only modification to the truck aside from some exhaust is a 180 or 170° thermostat. Lowering the thermostat temp stops/reduces the oil vapor consumption issue the 8.1 has. And to me these plugs look like the truck consumes oil still but frankly I am hardly seeing any consumption. The only unusual circumstance prior to the plug change was I had this thing idling for probably an hour and a half in the hundred degree weather we had while I have someone sitting in it with the AC on so I could bleed the brakes.

Differences, starts a tad quicker, exhaust smells different, idle is smoother though I liked the way it ran with the old plugs. Mpg was 10-12 prior. Put NGK blue plug wires on it too.

View attachment 348807

View attachment 348808

Parked at a random vacant house

View attachment 348809
Super nice LT + you made a good improvement …
I’d run it a year and then pull an easy to reach plug …
 
Almost all 8.1's burn oil. Check the level every fillup and top off. Those plugs look like hell, no autolites are not correct and are hot garbage.
 
The fine wire plugs you took out were not correct for your truck. 170 thermostat? Even in the 60's we ran 180. Your truck probably came with a 195 and that's what I would be using.


I checked my old emails and it is a 180°. The prior owner didn't put it in that was after the sale. These trucks have a weird internal PVC system that make them ingest oil vapors that ends up looking like pretty healthy oil consumption which this truck did do. Alot of guys bump the viscosity up and lower the operating temp with a thermostat swap and it mostly or entirely eliminates consumption. The only permanent fix is to pull the whole intake manifold and do a little aluminum welding.
 
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