New Owner - Oil weight for 278k mile Tercel?

[Zooler]

Hello everyone,

I was googling and came across this board. I am a new owner of a 1983 4WD Tercel with 278k miles .

I am wondering whether go to with the default 10w-30, or to bump it up to a thicker oil. I am in California.

Thanks!

[jimcrazy]

every likes something different, i run castrol 20-50 in my wagon and rav4 good and thick lol

[dlb]

it depends on how the engine has been looked after. if it has not had regular oil changes throughout its life, it could probably stand for thicker oil. you could do a compression test and hook up a mechanical oil pressure gauge. if any of those readings are low, you could try 15w-40 and see if they improve.

but i would honestly just run 10w-30 and see if it consumes it at all. if it does, you could do a seafoam oil treatment and/or restore oil additive and/or try 15w-40. you'll know within a few tanks what it needs.

[Petros]

the owners manual recommends oil weight based on outside air temperature your will be operating in before the next oil change. the california deserts or central valley in summer is very hot, the heavier wt. oil would be best, but cooler northern or coastal areas would need lighter wt. oil. On a car with that many miles on it I would not use the low viscosity synthetic oil, but use regular motor oil and perhaps add some STP or similar oil additive since the new oils do not have any zinc in them, which our engines were design to use.

for operating in temps 50 deg F and below it is 5W-30 or 10W-30;
for operating in temps about 30 to 70 deg F, 10w-40 or 20W-40;
for operating in temps 80 deg F and above, 10W-50 or 20W-50.

[irowiki]

There's nicer higher viscosity synthetics too.

[lannvouivre]

for operating in temps 80 deg F and above, 10W-50 or 20W-50.

Oops.

[Zooler]

for operating in temps 50 deg F and below it is 5W-30 or 10W-30;
for operating in temps about 30 to 70 deg F, 10w-40 or 20W-40;
for operating in temps 80 deg F and above, 10W-50 or 20W-50.

Wow, 20w-50 for any operation over 80 degrees? That seems really thick. I'm not very familiar with the 3A(C) engine. But, I've owned other small 4 cylinder Japanese vehicles and 20w-50 seems pretty thick lol.

[Zooler]

There's nicer higher viscosity synthetics too.

What are your thoughts on switching a 278k Tercel over to synthetic? Might clean out crud around the seals and make any existing leaks worse?

[rer233]

That's what i've heard. Been running castrol 20/50 in my tercels for 20+years now and NEVER had a lubrication-related failure.

[irowiki]

I bought my 83 and it was already running Mobil 1 synthetic, and gets fantastic mileage, so why stop? Mind you, zero leaks, no burning. Would not run synthetic in a burning or leaking engine.

Synthetic oil handles extreme hot and cold better, so it is a good match for weird new mexico.

My 87 on the other hand seems to burn some oil at higher rpms (such is the life of an auto) so it will not get synthetic. Right now it is getting some sort of synblend I got for a buck a quart.

My Camry on the other hand, suggests 5w-30, but since the bearings were towards the upper limit, I'll be running 10-40w synthetic.

[Zooler]

Thanks for the replies.

I was just reviewing the owners manual which came with the vehicle (photos below). On the back, it lists 10w-30 or 10w-40 as what to use under 'normal' temperatures. Then inside, it has the viscosity matrix that Petros posted above. So, is over 50 degrees not 'normal' according to Toyota? Seems confusing.

Also, and correct me if I am mistaken, my understanding is that engine operating temp should be independent of the outside environment (provided the cooling system is function). So, if a 30 weight is suitable at 50 or 60 degrees, would it not also be suitable at 90? Once the engine reaches operating temp, the oil's viscosity is at it's second number, is that right?

And, how about at cold start-up? Does a 20w oil circulate and lube and engine as fast as a 10w?

Thanks for any thoughts.

[irowiki]

If it is really hot out the car won't be cooling quite as well and things like the oil will be stressed out more.

[Petros]

engine operating temperature (as measured in the coolant) is not related to oil operating temperature. Demands on the coolant tend to go up with throttle position, as in driving up a long steady hill (more fuel to burn means more heat to remove by the water jacket). If your radiator and t-stat are working properly than you should have plenty of cooling capacity for the coolant.

No coolant circulates around the crank or the oil pan, so the cooling system does not affect oil temp. From lots of engine testing on dynometers I have done for various employers in the past, and also having a separate oil temp gauge (measured in the oil pan), oil temp is determined by sustained engine rpm. the higher the average RPM, the higher the oil temp. Race cars that are always running at near red-line need engine oil coolers. Note that even at large throttle settings, but low engine rpms, oil temps are not affected much (such as climbing a long hill in your car at modest speeds).

When I had a car with an oil temp gauge that I installed (sender in the oil pan), I noticed that for most city driving oil temps stayed way below optimum (about 180-200 degrees), and it only climbed when at high speeds on open highway driving, the higher the average speed, the higher the oil temp. Never had I saw the oil temp ever get near 200 deg, even when driving 85 mph across the Mojave desert in 100 deg F temps. Average air temps did not have as strong affect on oil temps as much as engine rpm. I had an oil cooler I was going to install on this car, that I had set up for doing rally cross, but was also my daily driver. But after driving it for over a year, even in a few rally events, I never saw the need to cool the engine oil further and left it off.

On very cold days high viscosity oil will slow the cranking speed, and the lighter weight oil is required, and there is some concern in very hot climates when driving the car at high speeds (as in crossing the dessert), they are concerned with enough oil film tension in the bearings. Synthetics work by having a very high film tension at low viscosity. So they reduce the viscus drag on the moving parts of the engine.

However, as pointed out, the thinner oil will also seep past rings and seals, particularly on a high miles engine. So it seems a waste of money to consume synthetic oil trying to save fuel economy, because you will not get much improvement in MPG. bearing friction is only about 5 to 10 percent of the total engine losses, so if you lower the friction by what? 20 percent perhaps (a guess), that would improve fuel economy by 2 percent. not sure you would even notice that, a tank of gas will take you about 6 more miles. changing the way you drive will have a much bigger effect than synthetics. And if you spend twice as much on motor oil to get 2 percent improvement, you wasted a lot of money, because synthetic oil costs a lot more. I also wonder what the long term effects are running an older engine design that was intended to use regular multi-vis oil, vs. low viscosity synthetic.

I buy cheap multi-viscoity oil, or synthetic blend you can get on sale for a reasonable price, and also add STP to put back the zinc they took out of the oil. And change it about 5000-6000 miles (about every six months), or if it is looks particularly black and looses that slippery "feel" on the dip stick.

[Zooler]

Very interesting Petros. Thanks for posting that explanation.

It is interesting to hear how different demands affect oil temp. And, that temp is independent of coolant. I feel I learned something today.

Would you say that 10w-30 is simply too thin for a general application (in any warm weather) 3A oil? Or, is it ok?

Do you have a sense of what concentration of zinc you have after adding the STP?

[Petros]

using 10w-30 with some STP would likely work well for all driving conditions except where it is routinely over 80 or 85 deg F. For hot climates I would not use anything less than 10W-40. I am using 5w-30 synthetic blend, with STP, where I live in Puget Sound area year around, though it does not get very hot here, only a few days in the 80's a year (I think the record high for Seattle ever recorded is only 94 deg). But I have a fairly freash engine, zero time about a year and a half ago (perhaps 15 to 20k miles).

I use one small bottle of STP, it seems to reduce oil consumption on worn engines. sometimes I use half a bottle since the 3a holds a little over 3 and 1/2 quarts. Though it does not cost much, I get it at wal-mart auto dept (where I also get the synthetic blend oil at a great price in 5 quart jugs).

If you have a lot of miles on your engine you can do the Seafoam engine treatment to clean it out, flush and fill with new oil, and add a seal conditioner (it will soften old seals, if you have new seals I would not use it). Than you can likely use the synthetic blend without consuming very much between oil changes.

If you go through more than about a quart every 1000 miles, just buy the cheap stuff, you will loose it faster than you will wear it out.