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10w-30 vs. 5w-30


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#16 Jeff726

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Posted 20 April 2004 - 09:20 PM

I may go with a 10w-30 next change then. :)

#17 Guest_sx460_*

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Posted 20 April 2004 - 10:59 PM

Is it just me, or does a 50 weight oil sound a little thick on a car with 3K miles?

#18 EddieS

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Posted 21 April 2004 - 09:03 AM

Toyota does not prohibit use of 10W-30. The 2003 & 2004 Corolla owners manuals simply recommend 5W-30 for easier starting in cold weather and best fuel economy.

In my experience, there is a negligible fuel economy penalty using 10W-30 in summer.

I agree with Slalom44 that 5W-30 is best in winter and 10W-30 best in summer.

In Phoenix I would use 10W-40 in summer because it's like a furnace there - 115 during the day, 100 at midnight and 90 at 7:00 am in the morning!

My owners manual and yours differ- on my 2003 corolla, the owners manual says on page 211, "If SAE 5W-30 oil is not available, SAE 10W-30 oil may be used. However, it should be replaced with SAE 5W-30 at the next oil change."

#19 friendly_jacek

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Posted 21 April 2004 - 03:16 PM

Is it just me, or does a 50 weight oil sound a little thick on a car with 3K miles?



http://theoildrop.se...ic;f=1;t=006320

See the above for illustration.
It is not Re: Corolla but for illustration purpose

#20 Cherry128

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Posted 22 April 2004 - 08:52 PM

5W30 should be fine. Keep in mind on a liquid cooled car with a poperly operating cooling system, the oil temp and engine temp will be only 10-20 degrees higher in 100 degrees than in 50 degree weather. Also, the oil temp at freeway speeds will be within 30-50 degrees. Not a huge difference. I've noticed the cooling system on my '03 corolla is significatly oversized. I've never seen the temp rise above 2/3 eveni in 90 degree weather in traffic towing a trailer.

The combination of a integrated oil cooler found in most modern cars, the aluminum radiator, dual ECU controlled cooling fans and a properly sized high flow thermostat, keep engien temps very even. THis is extermely importatnt to meet the ULEV (emissions) standards.

#21 bhp02

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Posted 23 April 2004 - 08:25 PM

cherry, just wondering what load you are pulling with your trailer on the
corolla ?? you have auto trans ??

#22 reyt32

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Posted 24 April 2004 - 05:13 AM

G'DAY,

I GOT NO PROBLEM USING SHELL ULTRA(FULL SYNTHETIC) 10/40 OR THE PENNZOIL 5W/50 (FULL SYNTH) IN THE SUMMER OR ANY OF THE SEASONS HERE IN THE SUNSHINE STATE OF AUSTRALIA, QUEENSLAND. SUMMER IN HERE IS VERY EXTREME AND ALSO COLD DURING WINTER AND MY COROLLA 7AFE ENGINE RUNS SMOOTHLY.

REY T

#23 friendly_jacek

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Posted 24 April 2004 - 06:36 PM

... integrated oil cooler found in most modern cars [...]. THis is extermely importatnt to meet the ULEV (emissions) standards.

Hmm, tell me which cars have this "intergrated" enginer oil cooler from factory.
My Corolla (2003) definitively has none. Oil cooler is usually installed in high performance, racing cars or as a towing package. I hope you installed one in your corolla as well as transmission cooler (if you have automatic) if you tow serious weights.

BTW, a stock temp gauge is not a reliable indicator of engine temp and especially not oil temp. You might want to invest in ATF and oil temp gauges.

Also, I would not use 5W30 in summer with towing, or any dino oil as well.
While I do not tow with corolla, I tow boat and other things with my AWD Subaru Legacy.
FYI, the subaru manual also calls for 5W30 averall, but 10W40/15W40/20W50 is recommended for towing (or driving at hight speed in desert/tropical areas). These are the conditions when oil temp skyrockets.
Good luck,
Jacek

#24 bhp02

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Posted 24 April 2004 - 08:55 PM

I've been towing a boat for 10 yrs in the summer with my minivan
with 5w30 dino oil. never had engine problems.

#25 reyt32

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Posted 27 April 2004 - 07:25 AM

g'day,

my 98 corolla ae112 (e11 in europe) was built and assembled in japan then exported here in australia. it has a factory oil cooler on it. i havent check those ae112 assembled here in australia from 1999-2000.

rey t.

#26 jfvoelk

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Posted 10 February 2007 - 11:17 AM

I will not claim to be a chemical engineer, but my dad was. I was told when I was a teenager "1970's" that if I put the 20-50W oil
in my 70 Torino I would shorten the engine life, he explained that the engine tolerances were machined with specific gaps, these
gaps allow oil to lubricate. Placing heavier oil in the engine will now allow full lubrication and cause excessive ware until the engine
wares out enough to allow the oil to penatrate. So I put straight 30 weight in it. (still have the car.) I owned a 1985 corolla
ran 5-20W synthetic in it, changed oil every 10K miles, Over 300k and used less than 1 qt every oil change. I drove 145 miles
a day to and from work, 3 timing belts, 1 alternator, 1 thermostat, (lots of breaks, tires, struts,plugs). Basically the engine,
and carb were never touched. Hope this helps, a good synthetic and regular change intervals, 4 months max or 10,000 miles.

#27 modestobulldog

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Posted 11 February 2007 - 02:00 AM

All 30W, 5W-30, and 10W-30 oils have a viscosity that is within a certain range when the engine is hot. That is by definition. To get a 5W-30 oil to be thinner than a 10W-30 oil at cold temps, the oil manufacturers typically use viscosity index (VI) improvers. Actually, they start with a thinner base stock, and the VI improvers act thicker when the oil is at temperature. So when comparing a conventional 5W-30 and 10W-30 oil, the 5W-30 oil starts with a less viscous (thinner) base stock to achieve the same viscosity when hot.

The problem with VI improvers is that they tend to shear down over time, thus making the oil less viscous (thinner) at high temps. The more VI improvers used, the more of this tendency. The longer you keep your oil in your car and the more hard driving, the more it tends to shear down. It's not a problem if you change your oil every 3-4000 miles, but it is nevertheless an issue.

So if I were living in a hot climate, I'd use 10W30 in the summer and 5W30 in the winter. Heck, I do that and I live in Ohio.

FYI: synthetics are a different story, since most synthetic 10W-30 oils have such good properties at cold temps, they don't even need VI improvers. I believe that is the case for some 5W-30 oils as well (if you believe what you read). And many brands use better (and more expensive) VI improvers that are more shear-stable, so even if you use a synthetic 5W30 in the desert, the loss of viscosity is negligible.


I work for a major oil company in Finance, and 3 years ago I sat in on a training session for our lubrication marketers. Our brand is often offered at a good price after rebate at Kragen. As I recall, he said our 10W30 is a "Group 2" base oil, the 5W30 was a "Group 2+" and had better oxidation (breakdown) characteristics. He said the Group 2 can't stretch to the 5 weight. I have been using 5W30 ever since. Of course, synthetic oil has better characteristics, it's advantage over conventional oil is much greater in cold weather than hot weather and also in higher performance engines beacuse they have tighter tolerances. The trainer said 10W30 conventional was fine in my corolla, but if I can get the 5W30 for the same price that would be better. My corolla has 221,000 miles and still going strong. As for the new high mileage motor oils, the are big money makers (for the oil co's and DIFM's - Do it for me). He suggested regular regardless of mileage unles your engine has symptoms. The bottle suggests > 75,000 miles .

Also, using a oil thicker than 10W30 in a VVT engine seems stupid to me. If you are under warranty and don't have a recommended weight, kiss your warranty goodbye and prepare to fork over $6,000 - $8,000. I guarantee they will find out. In fact, I bet it is one of the first things they check. I don't think Toyota will feel compelled to bail you out of your own stupidity for not using the correct oil.

Your comments on VI line up with what I rememberfrom the trainer. The thinner base oil comment is incorrect, it is refined in a different way. In fact Group 2+ costs more to refine than Group 2. I hope none of your brands of dino oil are using Group 1 base oil.

Edited by modestobulldog, 11 February 2007 - 02:17 AM.

#28 TRCar54

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Posted 12 February 2007 - 07:58 AM

The Toyota engineers that designed the engines have specified what oil is best for your engine. Usually they give a chart which makes recommendations based on the ambient temperature. I'd follow their recommendations.

5W-30 or 10W-30 in theory won't help your situation as each is 30W when at operating temperature.

If you're really concerned about heat, run a full synthetic.

Jay in MA

My Corolla recommends 5w-30 oil.

But I live in Arizona where it doesnt get below 30 degrees Farenheit, and can get well above 115 degrees in the summer.

So I am thinking that 10w-30 oil would be better for my conditions, but the corolla manual does say to use 5w-30.

What do you think?


Edited by TRCar54, 12 February 2007 - 08:04 AM.