Changing Oil Grades In "Modern" Cars

Hey All,

I've got an oil change coming up on my '07 Scion tC.  Currently, I run the manufacturers' recommended oil weight of 5W-20.  I get about 2,000 miles to the quart in my 145,000-mile engine.  This engine has a recall for excessive oil consumption and the fix requires replacing the pistons.  Luckily, my car doesn't have the issue (Toyota cuts the line at 1,200 miles to the quart below 150k miles) but I wonder if anyone has any thoughts about increasing viscosity to 5W-30 in an effort to improve on my current consumption rate.  I searched on this topic because I remember this coming up previously.  Despite differing permutations, I couldn't find any previous thread or article.  However I did find a nice article by Tom Suddard about removing and replacing the reluctor ring on an LS3, which I read.  Thanks, Tom.

Thoughts?

I don't think it would make any difference for consumption but I don't think it can hurt.

I wonder if Bob has an opinion?

Check the car's manual, if 5W-30 is in the recommended viscosity range for the temperatures the car is used in, go for it. The factory-recommended viscosity is always on the lower/colder side of the range for the engine.

We had our 2AZ (08 Rav4) rebuilt over the winter, gratis.   It's new rings and pistons, plus headgaskets and typical replacement items.  Would have been ~3200 miles according to the R/O.  I sprang for a new water pump and serpentine belt, while they had it apart.

I suggest you try, if you're eligible, to do the consumption test again.  We had until 150k miles (had to complete the test before then!) I initially thought the criteria for the consumption was on a sliding scale.  They change your oil, top you up, and tell you to come back in 1100-1300 miles.  However, regardless of how many miles you've driven when you return, they still pour a quart in the engine, and recheck the levels.  I think this is flawed.  They should add 11/13 quart when you come back at 1100, 13/13 quarts at 1300 miles.  Since they don't, I recommend you cut it as close as you can to 1300, we got to 1289 or something. 

I think you're also able to provide your own oil. In that case, I'd find the cheapest 0W20 synthetic you can.  Make them prove/show you the dipstick level before sealing it up.  If you fail, I believe they have you drive another few hundred miles to validate.  Ours failed both (passed the previous two attempts, 20k or so prior), so they on-the-spot gave us a loaner car and had the car from Thursday-Tuesday.  

Highly recommended.  I just did the first normally scheduled oil change on it, and got out about 4qts from the sump.  Before, I'd get 2-2.5 max.  

Sorry I can't advise on the original question.  The book for our Rav says 0W20 or 5W20

Still going to burn the oil, but it's likely still in the OK range in the manual. Since you're in soCal, you could likely run a 5W40 DEO in that engine through the late spring summer and early fall. 

Honestly, 2000 miles per quart is good by Honda standard. They say it's OK for a quart every thousand. Unfortunately once an engine starts burning oil from rings, it's not going to stop. 

Bob the REAL oil guy. said:

Still going to burn the oil, but it's likely still in the OK range in the manual. Since you're in soCal, you could likely run a 5W40 DEO in that engine through the late spring summer and early fall. 

Honestly, 2000 miles per quart is good by Honda standard. They say it's OK for a quart every thousand. Unfortunately once an engine starts burning oil from rings, it's not going to stop. 

It might be fine for Hondas but not for Toyotas.  According to the factory, the problem stems from inadequately sized oil relief holes in the oil ring land.  They get carboned up and leave too much oil on the cylinder walls.  Since I have a 5-speed manual, I'm turning about 600 more RPMs at 80 mph than the automatic cars.  So my hypothesis is carbon buildup is not as acute in my engine as with others due to the higher RPM at all speeds.

To stylngle's point, I'm hesitant to bring my car to a dealership so they can pull the head, pull the pan and rods, hone the cylinders, and install new pistons on the old rods with the crank still in the motor.  It's not the way I'd do it.  I can live with the consumption as it is now.  I was just wondering if 5-30 would buy me another couple of hundred miles a quart.

Are you sure they just replace the pistons and hone the cylinders?

I wouldn’t worry about used rods, those shouldn’t really fatigue in a stock application. 

What I would worry about is the particulate from honing, head/valve condition/flatness,  and bore shape. Those are the things I would press them for answers on before they open up the engine.

If they can provide good answers, and do the top end, then you can always drop the oil pan and replace the rod and main bearings (as long as nothing is scored).

Jerry From LA said:

Bob the REAL oil guy. said:

Still going to burn the oil, but it's likely still in the OK range in the manual. Since you're in soCal, you could likely run a 5W40 DEO in that engine through the late spring summer and early fall. 

Honestly, 2000 miles per quart is good by Honda standard. They say it's OK for a quart every thousand. Unfortunately once an engine starts burning oil from rings, it's not going to stop. 

It might be fine for Hondas but not for Toyotas.  According to the factory, the problem stems from inadequately sized oil relief holes in the oil ring land.  They get carboned up and leave too much oil on the cylinder walls.  Since I have a 5-speed manual, I'm turning about 600 more RPMs at 80 mph than the automatic cars.  So my hypothesis is carbon buildup is not as acute in my engine as with others due to the higher RPM at all speeds.

To stylngle's point, I'm hesitant to bring my car to a dealership so they can pull the head, pull the pan and rods, hone the cylinders, and install new pistons on the old rods with the crank still in the motor.  It's not the way I'd do it.  I can live with the consumption as it is now.  I was just wondering if 5-30 would buy me another couple of hundred miles a quart.

First, as long as stuff is cleaned properly, an "inframe" is just fine.  I used to do Datsun engines all the time that way, back when 510's and 240Z's still roamed the Earth.

Second, I very much doubt a heavier oil will burn less.  Sometimes it is worse, because the heavier oil is stickier and harder to scrape off the cylinder walls.  Again, back in the olden days, we serviced a guy with a Volvo 245 GLT, and in those days, we recommended 20W50 for cars driven vigorously.  Switching from Quaker State to Pennzoil, before they were the same company, resulted in about three times the oil consumption.  Back to Quaker State, problem solved.  In the 80's, 20W50 Pennzoil was a racing oil, very sticky.

Third, give it a shot.  As long as it doesn't get too cold, you can probably go even heavier, but too thick and the cam phasers won't work properly, and the thick oil might take too long to get to important spots.

EDIT:  I think they don't hone the cylinders on those, so even less chance of metal particles.  I could be wrong, though.

If the oil returns are plugged then the rings are also STUCK and this is the real reason for oil consumption.

I would not stray from recommended viscosity with anything with variable cam timing, which is more or less everything made in the last few cycles.  The first step in diagnosing a VVT issue is "Is the oil of the correct level and viscosity?"  If no, replace oil with what the engineers calibrated the system for and retry.  Going from factory oil to anything sludgy-thick enough to actually affect oil consumption (going from 5W20 to 5W30 will do crap-all) will also affect the cam phasers.

What I WOULD do in your case is four quarts of ATF in the crankcase instead of oil. and drive it that way.  Change the filter after 200 miles and again after another thousand or so.  Won't hurt a thing (ATF is a 5W20 oil with different additives, and red dye) and it WILL do an amazing job of degunking.

Hey Time,

I've built 17 motors and am familiar with all phases of engine rebuilding.  Toyota dealers do the minimum work necessary for the recall.  everything I've read says the crank's in the motor when they hone it.  Additionally, they reuse the rod bearings.  New pistons and rings are fitted to the rods.  That's it.

If my engine decides it wants to eat oil like crazy, I'll pull the motor and go through it.  It ain't no thang.

Knurled. said:

What I WOULD do in your case is four quarts of ATF in the crankcase instead of oil. and drive it that way.  Change the filter after 200 miles and again after another thousand or so.  Won't hurt a thing (ATF is a 5W20 oil with different additives, and red dye) and it WILL do an amazing job of degunking.

I might just try this as soon as I grow a bigger pair of balls.

In reply to Jerry From LA :

If it helps. I ran ATF for about 6000 miles or so in my first Volvo's turbo 1.9l.  I tend to have a "WOT or nothing" attitude while driving.  It lived just fine.  The amount of gunk that got pulled out of the engine and found its way into the oil filter was fascinating, to say the least.

People say that modern oils already have plenty of detergents.  I say, well clearly they aren't working if things are getting carboned up, so you need to use something different.

They hone if spec requires it (they measure ring gap and piston to wall, iirc).  I pulled the filter and cut it open after 500 miles.  No particulate matter that I could discern , or find with a magnet.  If it helps, they drop both the lower and upper pans, so it's easier to keep important stuff clean.

Modern ATF typically has less detergents than good modern engine oil.   Many years ago, it was the other way around (which is where the rumors started).  ATF is thinner than many engine oils, which does give some cleaning ability.  But for the most part, things can be cleaned by running good oil (not cheap oil) and working the engine hard enough to get the oil good and hot, get the rings moving, etc. 

There's some evidence that MMO added to oil does some cleaning as well (at a minimum, it smells good).  But I've never had an engine dirty enough to find out.  

In reply to rslifkin :

Even if it's not "more" additives, it's "different" additives, which is often enough.

If the additives in the engine oil were working, the engine wouldn't be sludgy.  And I've done too many cars (MODERN cars) on ATF and observed mass amounts of gunk in the oil filter after running ATF but not on engine oil, to think that it's just a rumor.

Going to a good base stock synthetic engine oil will do the same thing. 

Bob the REAL oil guy. said:

Going to a good base stock synthetic engine oil will do the same thing. 

Thats good to know, i usually change teh oil of whatever car i get fairly soon after getting it even if its had a recent oil change. I usually do Castrol Syntech, or whatever its called now, ive had good luck with it so far and a 5 quart jug is cheap at walmart

I'm sticking with the 5W-20 for sure, due to concerns with the VVT.  One other reason for changing to 5W-30 is everything in my purview runs on the heavier oil.  My wife's minivan and my stepdaughters cars all use it. So I was thinking about having only one grade of oil on hand.

As I said earlier, my car doesn't really have a consumption issue, other than what one would expect from benign neglect from all the POs.  2,000 miles a quart will do.  The motor runs great and does not leak.

If rings are stuck, this usually results in pretty good clouds of smoke and a reduction in the local mosquito population.  I don't have any readily apparent symptoms of excessive oil consumption so I'll stick to Valvoline in the crankcase.  I wish our local NAPA store didn't move away.  NAPA motor oil is the "poor man's" Valvoline.  I'm paying full whack for the rich man's Valvoline.

In reply to Jerry From LA :

Every Saturn I have seen rebuilt during my time at the dealership were due to stuck rings.  They weren't mosquito-foggers.

Same for my experiences at the "indy" where I currently work.  Four quarts in 5000mi is not fogging for mosquitoes, but it certainly IS due in part to stuck rings.  And when you are pulling the head to fix all the belt valves after the timing chain jumped from lack of oil, or replacing the rod bearings that relocated to the oil filter after running out of oil, you get to see this firsthand.  I've had to chisel the rings out of pistons and use a drill bit (in my fingers, not a drill!) to clear the oil returns.

At Saturn we did a lot of in-frame engine rebuilds for oil consumption.  At the indy shop, I have cured the oil consumption on Saturns with a simple decarbonizing...

The gunked-up engines are usually caused by owner neglect.  Add a combo of the cheapest oil the quickie lube can use, plenty of short trips to chew the oil up quickly, never running the engine hard to get the oil hot and the rings moving and then waiting too long to change the oil (relative to when it's worn out) and you get nasty, gunked-up engines. 

Using better oil, driving the things harder and ideally doing an oil analysis occasionally to figure out how long the oil you're using lasts before it's worn out (so you know when to change it instead of guessing) leads to things staying nice and clean.