Going conventional

[Wingo]

I have decided to go backwards. My 2002 8.1L keeps eating oil even after putting in updated intake gaskets, and I am going to try conventional Valvoline. After talking to my father, older and wiser than me, he had a few examples of a few of his vehicles that consumed synthetic/semi-synthetic oil, but eventually took none when he switched to conventional. Only thing I can think of is it is dirtier and maybe accumulates at the top of the pistons reducing blowby.

I'm down, this engine was developed before synthetic oils were common and I am sick of adding oil. The intake gasket reduced it some, but I figured it won't hurt anything. I change oil at 3k. Anyone else ever have this result with old fashioned conventional?

 

[SureshR]

Do you want to try cleaning your PCV valve and PCV breather hose first? Oil gunk accumulating in them will lead to excess consumption regardless of whether you fill conventional or molten gold amsoil for that matter

 

[Wingo]

Do you want to try cleaning your PCV valve and PCV breather hose first? Oil gunk accumulating in them will lead to excess consumption regardless of whether you fill conventional or molten gold amsoil for that matter

8.1 doesn't have a PCV valve.

 

[ATex7239]

Give a shot. Good luck finding a straight old conventional though.

 

[Wingo]

Give a shot. Good luck finding a straight old conventional though.

It is still sold at my local farm/fleet store.

 

[CKN]

So basically the internals of the motor are shot. Oil is the least of your issues.

 

[puellarum]

My 89 blazer, 350 Chevy with the throttle body injection, used a lot of Royal purple synthetic. And also leaked. It just seems to like conventional oil better. I'm going to try it one more time with mobil1 5W30 and see what happens. But I tend to think that older engines just prefer conventional.

 

[Snagglefoot]

Even conventional is not really conventional if it meets SP. Maybe look for an SN or earlier designation. Good luck.

 

[Wingo]

So basically the internals of the motor are shot. Oil is the least of your issues.

Don't think so. No rod knock or piston slap. Rings may be worn. 80k on the motor, runs like a top, tons of power. But who knows.

 

[VolvoZ]

Sure. Try a different oil. May not stop the oil consumption, but might slow it. Example: 06 Honda Odyssey uses maybe a 1/3 qt per thousand miles on Mobil 1, Mobil Super Synth, Mobil anything. I’ve got over 30 oil changes in this van. Does not use anything when using any other oil brand. So, try something else. And report back with results, please.

 

[Wingo]

Sure. Try a different oil. May not stop the oil consumption, but might slow it. Example: 06 Honda Odyssey uses maybe a 1/3 qt per thousand miles on Mobil 1, Mobil Super Synth, Mobil anything. I’ve got over 30 oil changes in this van. Does not use anything when using any other oil brand. So, try something else. And report back with results, please.

Slow would be nice. Intake gasket did cut consumption by roughly half, so I am happy for that. If I can cut it in half again I will be happy with that. These big blocks do have a tendency to eat oil, but it doesn't have to be so dang greedy at it.

 

[cptbarkey]

Looks like a common issue with that engine. Some folks have made a catch can and seen success. Have a read and research more, good luck.

8.1L oil consumption fix

So I’ve been doing a lot of intensive research on the intake manifold/PCV system on these engines. I’m getting fed up with oil consumption and I’d like to share what I’ve found. The intake manifold has an integrated PCV system (no PCV valve), in which crankcase vapors are pushed through a small...

www.tahoeyukonforum.com

 

[Triple_Se7en]

Google BG EPR and MOA. Follow the directions and watch your consumption issues get cut in half (at least).
Run semi-syn oils. Supertech HM, Napa HM, are just two recommendations to save money.

 

[macarose]

I'm going to state this once and hopefully, this time, someone will listen.

"Conventional oils can be high quality oils. Valvoline happens to sell them."

There is absolutely nothing wrong with using conventional oil, or even opting for a $25 Pit Crew oil change, so long as your engine doesn't require synthetic.

 

[nickaluch]

My 2007 G6 beater has had 5/30 syn oil it's whole life but has been using a QT of oil at 1k lately. Switched to Valvoline 10/30 Dino not a blend and no makeup oil at 2K miles with plenty of idle time. Big difference so far .

 

[Graham Piccinini]

Big blocks in general are oil drinkers. The 454, the 8.1L, Ford 460, etc. There is no cure, but a 40 or 50 grade (if temps allow) does help with oil consumption.

A coworker happens to have a 454 Chevy GMT400, and a Ford 460 motorhome. Runs basic cheapest HDEO 15W40 year round. Usually SuperTech or Mobil 1300. Does bump it up to SuperTech 20W50 if motorhome is going to be traveling for a while in the summer. He still does 3000-3500 mile oil/filter changes and no noticeable oil consumption with 15W40 or 20W50 in those old mills.
I do recall (years ago) some 8.1L owner on this board claim to have similar results. I believe it was an Avalanche...

 

[oldhp]

What weight are you using? Maybe step up to a 15W40.

 

[Wingo]

What weight are you using? Maybe step up to a 15W40.

10w30

 

[Dudemanmaximus]

I owned a 2001 GMC dually with the 8.1 for 4 years. I bought it with 55000 miles on the clock. One manifold was bad replaced that and went through 2 more sets before finally putting headers on it. It would use 1.5 quarts or so of 5w30 every 3K miles. Like others say I think these motors like at least a 40 weight. When I used 15w40 conventional I had almost no oil consumption after 5K miles including a lot of heavy towing. The best oil I found for it was probably M1 15W50 or Mystic 15w50 which resulted in very little consumption. I did not get a chance to try 5w40 before I sold it.

 

[Wingo]

I owned a 2001 GMC dually with the 8.1 for 4 years. I bought it with 55000 miles on the clock. One manifold was bad replaced that and went through 2 more sets before finally putting headers on it. It would use 1.5 quarts or so of 5w30 every 3K miles. Like others say I think these motors like at least a 40 weight. When I used 15w40 conventional I had almost no oil consumption after 5K miles including a lot of heavy towing. The best oil I found for it was probably M1 15W50 or Mystic 15w50 which resulted in very little consumption. I did not get a chance to try 5w40 before I sold it.

What climate are you in? I am in the tundra of northern MN where it gets well below zero. I fear a 50 weight when that cold would be a little too stiff.