Who-dunit: Oil Consumption down 50%? ARX or Dino?

[outrun]

GM 3800 Series II

Running Mobil 1 & Amsoil .3 -.4qts per 1000miles were dissapearing

Right now I am running a bottle of AutoRX with Pennzoil yellow-bottled mineral oil (wash phase).

It has been 2,000 miles now and I am only down less than .3 qts! I will change the oil and filter and go to rinse phase at 3,000 miles.

So who is to blame for the drastic reduction in consumption?

Could it simply be the mineral base oil (GrpII+) of Pennzoil versus running PAO based M1 & Amsoil? There has been talk on here for years of some engines having higher consumption with true synthetics.

The only other variable that has changed also during this interval is me using very conservative driving habits to squeeze every possible mpg in this difficult economic period. I am not redlining or driving aggressively. In fact I am trying to keep all my driving at or below the 2,000rpm band. It is also my understanding that sustained high rpms can (but not necessarily) result in increased oil burn rates.

If AutoRX did this hooray! That is a drastic improvement for a pour in maintenence strategy.

 

[Gary Allan]

Easy to figure out. Go back to the "good oil" Amsoil and associate happy thoughts with it. If it's not consumed, then you chose wisely.

Choosing the "bad oil" M1 ..you will have dark thoughts even if it's not consumed.

(j/k about the good/bad thing

)

 

[daves87rs]

A bit of both, maybe?

 

[StevieC]

I would think ARX fixed a poorly sealing ring problem or a valve seal that wasn't sealing properly.

I would follow Gary's advice and change back to Amsoil and see what happens.

If it starts consuming you know Dino is the answer...

Besides, being in Texas weather with that excellent engine, I wouldn't worry about running Syn. Overkill IMO.

 

[outrun]

Stevie,

Your right, I have come to an oil-identity crisis realizing this engine will (seemingly) last forever no matter whats is run at suggested change intervals. Second, even though it is over-kill I can not make up mind.

There are too many outstanding lubricant choices out there now ... Amsoil, M1, Redline, Motul, Pennzoil Platinum, Chevron, Schaeffers, GC, LubroMoly ....It is enough to make your head explode. Then again as you allude to simple Chevron, Havoline, etc could all make this motor run forever also at 50% or more of the above products cost.

I will continue with the consumption observations. The car will hit 200k soon. That would be a wonderful time for a first ever compression and leak down test if the labor rate will not kill me

 

[StevieC]

Why do a compression test/leak down at 200K? I'm sure it's good if the engine starts/runs without hesitation.

I would put the money into a used oil analysis to what is the maximum time you can run a quality dino in that engine. If you get a Premium test from Terry he can even tell you if you have blowby and if your EGR valve is functioning. They have a very good lab that can tell you more about your car than you will ever want to know.

Then do a quality dino/filter change on the interval that is just slightly less than what the used oil analysis says is safe, and drive happy. Those engines are a very good design and would be one of the few GM products I would think about purchasing.

(Not one for "Domestic" vehicles)

 

[Turk]

Yes, increased RPM's in an engine can result in more oil consumption. I proved it in comparisons over and over in my Saturn.

 

[sprintman]

Run clean phase longer

 

[outrun]

It gets better now ... I will need need better documentation and perhaps even a scan gauge (an over due purchase anyway!) .... but my fuel economy has been seemingly restored to the EPA "old version" fuel economy ratings of 19/29 ... and I have observed somewhere around 20/30+ so far! Again I think this may be helped by three new Bosch O2 sensors, and a new Air Filter, and adopting safe hypermiling driving tactics.

 

[ZZman]

I think all three played a part: Oil, ARX and driving habits.

 

[StevieC]

I think it was more the 02 Sensors, the Air filter replacement and your hypermiling that did most of it, but ARX could have cleaned your piston rings and restored some compression adding to the overall mileage gain. Too many variables to say for sure.

 

[Gary Allan]

What it did, aside from any of its own effects, inspired him to give a darn about it. Before he'd written it off for what it gave him.

 

[outrun]

Final Stats! AutoRX wash phase completed with Pennzoil "yellow bottle" 5W30 SM. OCI was 4,000 miles and consumption was about .5qts (conservative overestimate, uncertainty due to oversize filter PF52 usage).

.125qts/1k = Pennzoil, ARX, no idling, light foot

.4qts/1k= German Castrol 0W30 (before above variables)

That makes for a reduction in consumption factor of 3.2x!!

Once I switch to PP, Mobil 1 Advanced Fuel Economy or Amsoil then I can test if this was a mechanical ring cleanliness issue or simply that this engine prefers mineral based oils to reduce consumption.