High Mileage oil question...

[fingpilot]

I consider myself pretty knowledgeable when it comes to oil. Have been running synthetics in turbines since 1970-something ( a pair of J-79's in a St. Louis low rider). Have had a long list of air, oil, and water-cooled engines since then.

Fast forward 45 years.

Behind my Cummins ISC powered pusher, is a lowly '04 Prius in an enclosed trailer. It has 209k on it. Like all Prius' (Prii some say), They start burning oil at 180k. I've owned it since new. Was broken in on dino, and after 15k, has been on Mobil 1 5W-40. Never used a drop between changes at 5k. At 195k, it started using 1 qt. over 5K. I would add oil at 1/3 stick. Now I go 3k and it needs a quart. It is bone dry under the hood, has never leaked a drop. Summer temps back here (Alabama) have been high 90's day to mid 70's night. 90% of my driving is interstate 70MPH. Winter temps here are 70's day to 40's night.

The Prius geeks are saying change to 10W-30 to help the burn, assumed to be rings. I did replace the PCV valve, no change. They say drive it till it dies.



My memory says that dino 10W-30 uses some different chemicals to get that viscosity, unlike any other dino viscosity.

So two questions, actually.

1) Does 10W-30 Synth (M1) use any 'tricks' to get that viscosity? (like dino 10W-30)

2) Does the change to thicker oil likely to change my burn quantities?

Thanks in advance.

[M.D. Holloway]

no tricks, done by base oil blending and a balance of additives. As for the oil use - I wrote an article about this many years ago. Here are the basics:

1. INCORRECT SET FOR JOB Check for oversize cylinders and use of standard ring set. Try several rings in cylinder and if excessive gap, you have incorrect rings. Recheck by having cylinder miked.

2. RINGS NOT SEATED. CYLINDERS SHOW AREAS WHERE RINGS DID NOT CONTACT
a) Cylinders distorted from heat or improper torquing.
b) Failure to deglaze cylinders properly. We recommend 220-300 grit stones.

3. RING INSTALLED WRONG
a) Compression rings not installed according to instructions.
b) Rings not installed in proper groove.
c) Rings incorrect for groove width.

4. RINGS SPINNING IN THE GROOVE
a) Usually side of compression rings will be highly polished.
b) Inside bore of Flex-Scraper will not show contact points of Inner Spring crimps.
c) Excessive blow-by.
d) Check for too much piston clearance.
e) Twisted or bent connecting rod.
f) Too much end play in the crankshaft.
g) More than normal vibration.
h) Cylinder walls highly polished or failed to deglaze cylinders.

5. RINGS STUCK IN GROOVE -(COMMON IN LATE ENGINES)
a) Improper side clearance.
b) Water seepage into cylinders.
c) Check cylinder head and block surface.
d) Check head gaskets.
e) Check for cracks.

6. FRACTURED OR BROKEN RINGS
a) Detonation, due to lugging, low grade fuel, improper ignition setting.
b) Over heating.
c) Careless installation when installing rings and piston in the cylinders.
d) Failure to remove cylinder ridge.




7. SIDE WEAR ON RINGS-TOP GROOVE WEAR-RINGS BADLY WORN
a) Abrasive.
b) Gas wash.
c) Water seeping into cylinders.
d) Detonation.
e) Worn groove, allows ring to pound.

8. RINGS SCUFFED
a) Lack of lubrication.
b) Low oil pressure.
c) Too slow idle during break-in.
d) Engine overheated, check cooling system.
e) Check for water or anti-freeze leaking into cylinders and destroying lubrication.
f) Failure to clean carbon from corners of groove.
g) Distorted cylinders.
h) Improper torquing of cylinder head.

9. CRACKED OR BROKEN RING LANDS
a) Detonation.
b) Pre-ignition.
c) Failure to remove all the ridge before removing pistons.

10. CRACKED PISTONS
a) Common in late engines, extreme pressure due to carbon deposit in combustion chamber.
b) Detonation.

11. TIGHT PISTON PINS Will affect the free action of the piston, resulting in rapid ring failure, piston and cylinder damage.

12. CHECK CYLINDER TAPER Check the cylinders at the top of the ring travel. Many high compression engines will have a sharp taper and out-of-roundness in the top half inch. V-8 engines generally wear more on the left side (sitting in the driver's seat). Check all cylinders. Don't take a chance.

13. CHECK PISTON CLEARANCE Mike cylinders and pistons. Feeler gauges bridge the wear spots and do not give a true picture. Failure to resize pistons will shorten the life of the rings due to the rocking action of the piston.

14. CHECK VALVE ASSEMBLY The first step should be the removal of intake valves. Check under the head of the valves and the valve ports for an oil or carbon deposit. A deposit will indicate oil is being pulled into the combustion chamber due to a faulty booster pump, defective positive type breather system, or past the valve stems. A complete check must be made.

15. CHECK CRANKSHAFT Mic the crankshaft rod journals for size, out-of-roundness and taper. Remember when bearing clearance is increased from .0015 to .004, you will have 6 times more oil thrown into the cylinders.

16. CHECK BEARING INSERTS Check the inserts for fractures, wear and scoring.

[Nostril Cheese]

I switched to Mobil 1 10W-30 a couple years ago in my '94 Trooper. 252K on the clock. It cured a persistent lifter tick and really helped bring down oil consumption.

just my 2 cents.

[fingpilot]

Thanks Mike, I am not going to open this engine up.

Thanks King, that's my next step.

[M.D. Holloway]

Problems can be solved by medicine (oils), surgery (wrenching), or sometimes they just self correct (which some say is an act of God).

I have know folks to use a thicker oil 10W40 as well as thinner oils a 10W30. The last set of digits represent the viscosity at operating conditions. The first set is cold crank and cold pump viscosity.

[Joe Bob]

Go with a straight 30 or 50w dino. See what happens.

[1990C4S]

If you're using 5W-30 and go to 10W-30, I don't see how that will make much difference, they are both 30W oil when warm.

If it's warm there I would be tempted to try a 20W-50 for 3,000 miles.

In theory that should cut the loss.

[Scott Watkins]

Royal Purple.

[widebody911]

Originally Posted by Joe Bob

Go with a straight 30 or 50w dino. See what happens.

I was going to say 60w

[Joe Bob]

Changing brands won't help, you would just burn more expensive stuff. Bad rings needs either new rings or thicker oil.....

[beepbeep]

Originally Posted by 1990C4S

If you're using 5W-30 and go to 10W-30, I don't see how that will make much difference, they are both 30W oil when warm.

If it's warm there I would be tempted to try a 20W-50 for 3,000 miles.

In theory that should cut the loss.

This.

10W-30 and 0W-30 have same viscosity when warm. 10W-30 till be harder to crank when cold though.

I would try 10W-50 + seal sweller agent and see if it helps.
A sudden raise in oil consumption is signalling a leak (sometimes, crank seal leak will spread the oil around so it is not readily visible).

... or valve stem seals got brittle.

[Porchdog]

You are unhappy that you need to add a quart every 3,000 miles?

My 94 Golf took a half quart every couple thousand miles from the time I bought it (with 30K )until I sold it (with over 200K). I can't say I ever thought it was an issue.

The "high mileage" Mobil 1 seems to help valve noise on startup with my 98 K1500.

[bkreigsr]

Stop guessing and send a sample to Blackstone Labs.
Bill K

[M.D. Holloway]

Blackstone? The horror!!! I will pay for you to send it to ALS Tribology!!!! Send me a PM and I will send you a free kit to test your oil. I would rather have you not test it then to send it to anyone other than ALS Tribology...

[Otter74]

Originally Posted by M.D. Holloway

Blackstone? The horror!!! I will pay for you to send it to ALS Tribology!!!! Send me a PM and I will send you a free kit to test your oil. I would rather have you not test it then to send it to anyone other than ALS Tribology...

Why? Do explain. And if you feel so strongly about it, will you send me one, too?

[Joe Bob]

Me too!

[Don Ro]

Me three!

[sand_man]

...umm, four?

[911 Rod]

A fifth to Canada?

[fingpilot]

Originally Posted by 911 Rod

A fifth to Canada?

Didn't you guys used to send fifth's to us?