Sienna Saga

[ericthepig]

Here's a "quick" (might want to grab a cup of coffee) update on my '98 Sienna (151k miles) -

History -
1MZ-FE "sludger" engine.
Bought at 62k miles.
80k miles (62-140k on M1)
Oil consumption was consistent (last several years) at 1 qt in first 1k and 1 qt in subsequent 1.7k of an OCI.
Last Summer (2007) - 500 mile Neutra 131 run.
Last Thanksgiving - 1k mile Neutra 131 run.
Filled with Schaeffer 9000 5w30 - ran this from end of November 2007 to early April 2008 (3.75k miles - perhaps two 150mile round trips on this, all other miles were mostly 3 mile round trips - will post my UOA "soon").
Consumption after Neutra runs had dropped perhaps by 40-50%. Thought I might have a slow leak (later notified by brake mechanic that I had a slow leak from the oil pan - so slow that there are no drips).
Installed Schaeffer 15w40 in April (I was thinking the leak was insufficient to account for consumption).
Consumption at 1k was unchanged w/ the 15w40. Since I'm now in a period (and have been for about six wks) of very high mile trips (will average out to about 1k every two wks between now and July 4th) - I decided to try something ...

Bugging me in the back of my mind was what I read last year by AEHaas - that is, thin oils possibly lessening consumption. I like to do long OCIs, and having high consumption (and thus frequent top-offs) runs counter to the philosophy/theory/practice of the long OCI (very frustrating). I was going to be bummed if I never gave Haas' theory a try - so, I decided to take advantage of this period of high miles to test things. I dropped the Sch. 15w40 out (into a clean, air tight container - I'll find a use for it), and I dropped in Penz. Plat. 5w20 (it's thin among the 20w's) (btw - haven't chged my PureOne filter since last November).

I'm now at 1.2k on the PP 5w20. Consumption is either equal or less (definitely not more) than the 15w40. In fact, out to the 800 mile mark, there was almost no discernable movement of the oil level from the "full" mark on the dipstick. I haven't seen an oil do this in this vehicle in about five years.

Conclusion -
All the conventional wisdom is - thick oils for older engines, thick oils for consumption. This Toyota engine may not be old yet (may still have new tolerances), but there is the consumption issue. 5w20 hasn't fixed my consumption (perhaps it's all due to the oil pan now), but it's definitely not consuming at a higher rate. So it can be said that in this engine, a thin oil does not lead to higher consumption.

A thin oil helps my peace of mind in this vehicle that can go the whole school year on mostly 2-3 mile round trips (school, church, Wally World, groceries, restuarants - all are very close). I'm not totally at peace w/ PP in this app (esp. since it's now going to see heavy and hot hiway miles). PP didn't score well on Amoils heat resiliancy test (compared to Amsoil and M1) and this engine is known for heat - but I'm planning to leave it in till around Thanksgiving and then UOA.

Thank you for your time.

 

[artificialist]

Have you replaced your PCV valve? Sometimes they stick open and let oil exit freely.

 

[ericthepig]

PCV never chged. Plan to do that.

Dealer said oil pan fix would be $420 (apparently they have to pull the engine - actually I think the exhaust has to come off - but I'm going to get a second estimate from the local independent mech.

BTW, on the thin oil vs consumption - I wonder if my previous trend - 1qt in 1k, 1qt in subseq. 1.7k was due to the oil sheering some. Perhaps it would get thinner and then consume less. (?) Hard to decipher that consumption trend (which was very consistent).

 

[ericthepig]

One more contradictory tidbit -

My van historically has gotten 24.5 mpg in pure hiway driving (Mobil 1 xxw30).

With the Schaeffer 15w40 installed, I got 26+ mpg on a ~150 round trip (pure hiway). Short trip, so error in the measurement will have more effect - but I always try to fill to the same pt each time.

With the PP 5w20 installed, I've gotten 22.5 mpg on that same 150 mile trip (twice now).

I don't understand any thing any more.

 

[artificialist]

I have been told that thicker oils can improve ring seal, and the reduce loss of power through blow by more than makes up for the oil pump working harder.

 

[ericthepig]

We're doing a long (1k) trip this wkend (as well as many other wkends between now and mid-July).

On long trips this van consistently hits between 24.5 and 25mpg. If I continue to get 22ish mpg on this next trip - then there's a high likelihood I'm dumping this PP 5w20 (mind you into an airtight clean container) and putting the Schaeffer 15w40 (from it's airtight clean container) back in. Lots of "ifs" here - but if the 15w40 gets me back up to my original (or higher as stated above!) mpg - then I'm done with the 5w20 (at least for the summer).

 

[ericthepig]

Reporting in on the first 2.2k miles of Penz. Plat. 5w20 in this 98 Sienna -

Total oil consumption at 2180 miles is 3/4 qt (that's outstanding compared to this vehicle's history). I knew things had improved after my Neutra flush last Summer and Fall (after which I ran Sch. 5w30 and Sch. 15w40) - so I can't say that the 5w20 definitely has less consumption - but I can say that it hasn't increased conumption any over the heavier wgts.

This is all with the oil pan gasket leak.

Gas mileage with the 5w20 on this wkends trip was -
26.4ish mpg (first reading)
22.5ish mpg (second reading, but fighting head wind gust coming in at an angle).
24.5 mpg
and
26.5 mpg on final home stretch.

Those are excellent for this vehicle - so those readings I saw a few wks ago of 22.5mpg seem not to be the norm - my wife made those trips - perhaps head winds there also (?)

So it's steady as she goes this Summer for the coming long trips with the PP 5w20.

 

[MC5W20]

Just going to make a wild guess here. It seems your 15w40 Schaf oil has some outstanding anti-friction properties to get the increased MPG's. The only other thing to consider is the wind. Was it helping you or blowing against you in any of these comparable trips?

 

[ericthepig]

Originally Posted By: MC5W20
Just going to make a wild guess here. It seems your 15w40 Schaf oil has some outstanding anti-friction properties to get the increased MPG's. The only other thing to consider is the wind. Was it helping you or blowing against you in any of these comparable trips?


Yes. There was head wind in the 22.5 that PP gave me. And I may have had a tail wind (though not much) in the final PP reading of 26.5. But for the Schaeffers reading of 26+ mpg I didn't pay attention to the wind - however, it was a round trip w/in a matter of hours - so I think it would cancel out.