Oil Viscosity

john in la · Aug 2, 2015

George's post below got me to thinking.

Both my Ford and Toyota calls for 5W-30 oil
I have never used that oil in either car but I live where it gets below 32 degrees for only a couple of hours per night a few nights a year.
I have always used 10W-40 oil. If that is sold out I will buy 10W-30 oil.

I can not see how a car manufacture can put a sticker on a car that works the same on the gulf coast and on the great lakes coast. Different weather needs different oil.

So do you use the manufacture recommendations when you pick a oil or do you consider your climate into the equation.

RMinVa · Aug 2, 2015

I use manufacture recommendations on the newer models that use 5w-20 and 0w-20. Anything above that I may vary a little. Depends on milage.

Steve@Advance · Aug 2, 2015

I would carefully use what the mfg calls for, especially if under warranty.

Anything with variable valve timing needs what it was designed to work with.

ShadetreeRet · Aug 2, 2015

What does the glove box owners manual recommend? The engines that are being manufactured now have very close tolerances, this is the main reason for requiring lighter weight oils, so the oil will flow freely through these smaller-than-used-to-be tolerances or clearances. The factories do a considerable amount of testing before deciding what oils to use and they sure don't want to replace any engines while under warranty. Actually, if an engine fails under warranty and they determine the wrong oil had been used the owner will likely have to foot the bill.

JF in MI · Aug 2, 2015

I have a new car that stipulates 5W-20 synthetic blend. I don't think I've even seen 0W-20.

notjustair · Aug 2, 2015

Yup, they say 0-20 or 5-20 for the pickup. I guess that gives you lots of options to thicken it up when the engine gets worn!

Texasmark1 · Aug 2, 2015

Check out Mobil 1 in the green label. WW carries it. Blasted across the front of the gallon container is a posting"Made for Hondas and Toyotas". Mobil stands behind vehicle warranties for the 0 exceeding the requirements of 5w and 10w.

I had an '09 Ram Hemi with the 4+4 and it used 5w-20 also. The owner's manual said that the oil pump was made for that light oil and that the 4+4 function was unreliable with higher viscosity oil.

Current 2011 Silverado is 5w-30 Dexos which seems to be semi-syn. I use Mobil 1 0w-30 which is Dexos rated.

Russ from MN · Aug 2, 2015

The cooling system has a thermostat, so they run at similar temperatures regardless of the ambient temperature, I would use what the manufacturer recommends, also, you will get better mileage.

Texasmark1 · Aug 3, 2015

Besides being better for your engine during the critical first starting seconds, thin oils fit into the better fuel economy envelope. That's one reason Mobil 1 flaunts their 0w oils and put a "go green" label on the containers.

I have been a heavy hard liner on keeping the oil pressure up when the engine gets hot over the years, aka heavy oils. But back in 2005 when I bought my first "modern engine design" Dodge 1500 I started to realize times and oils have changed and it's time to bring my way of thinking up to date. Course my C rated engines still get C rated oil and that's 15w-40 or 5w-40 full syn. Rot T.

Traditional Farmer · Aug 3, 2015

For the last 15 or more years I've run Kendall 15W-40 diesel grade oil in the many
engines I own and run and never had an oil related problem that I know of and I have some very high mileage/hour motors.

GVSII · Aug 3, 2015

If your engines have variable valve timing, higher than specified viscosity oil could cause problems.Might not too.Your engines - your call.

Stephen Newell · Aug 3, 2015

Oil is hard to guess. I bought a 1975 jeep and put a rebuilt motor in it. Because of it's age I put straight 30w oil in it and the oil pressure would run about 10 psi on the highway when it's suppose to get 37 psi. I was convinced the oil pump I got with the motor was defective so I replaced it and the oil pressure ran the same pressure. Then a couple years later I needed to change the oil and store I went to was out of 30w oil so I used 5w-30 oil. After changing the oil the oil pressure started running at 37 psi highway with the 5w-30 oil.

NoNewParts · Aug 3, 2015

depends on what's inside the engine I guess.
Last new truck I had, 07 GMC (gave it to my son...hated the automatic....lol...another thread for that..)
It had 'active fuel management'
Didn't have a clue about how it shut down half the engine....so I read about it...
hmmm....oil based control.
after reading, I used exactly what was called for, and changed it at half the recommended mileage....
wrong or dirty oil would have messed it up.

Mike M · Aug 3, 2015

Years ago GM had a service bulletin out about NOT TO use 10-40 anymore because it was leading to excess carbon on top of the pistons. They then went to 10-30.

RMinVa · Aug 3, 2015

I use Amsoil. They also make 0W-30. This is their signature series oil 100% synthetc. Rated for 25,000 miles. They pretty much have any oil weight that manufacturer says to use. I use 0W-20 in my Honda Fit 1.5L

W_B · Aug 3, 2015

I wouldn't try to out guess years of research... use what is recommended by the mfg.

sotxbill · Aug 3, 2015

Thinner oils can give up to 2% gain on mpg... and the CAFE rules are eating their lunch. (Corporate Average Fuel Economy)

And as others have said... varible timing, oil fired injectors, and other technology is sensitive to oils and additives now.

old popper · Aug 3, 2015

Back when I bought my '05 Super Duty, I questioned the dealer about the use of 5W/20 oil in our 90+ summer temps here in Iowa. He told me that there are such close tolerances in the modern engine that heavier oil would blow seals, and fail to lubricate some things. I took his advice and used nothing but 5W/20.

dhermesc · Aug 3, 2015

Agreed. Putting a heavier oil in a new tight engine will cause as much wear in a few thousands miles as years of wear.

While "lighter" oils may not stand up to heat over a long period of time as well as heavier grades of oil you can beat that issue by changing the oil more often. While that is expensive in a Super Duty with a diesel - in most vehicles its 5 or 6 quarts (8 with the newer Ford 5.0) of oil and a regular duty filter or about $20 to $25 if using a name brand oil. Cheap both short term and long term.

dhermesc · Aug 3, 2015

0-20 and 0-30 are on the shelf at Wal-Mart and have been for a while - only in synthetic though. A conventional oil can't handle the that kind of multi-grade range and be effective.

GVSII · Aug 3, 2015

(quoted from post at 06:21:09 08/03/15) Years ago GM had a service bulletin out about NOT TO use 10-40 anymore because it was leading to excess carbon on top of the pistons. They then went to 10-30.

Back in the "70s a GM engineer said 10 40 never should have seen the light of day.Now some small engines call for it.Go figure!

GVSII · Aug 3, 2015

(quoted from post at 06:21:09 08/03/15) Years ago GM had a service bulletin out about NOT TO use 10-40 anymore because it was leading to excess carbon on top of the pistons. They then went to 10-30.

Back in the "70s a GM engineer said 10 40 never should have seen the light of day.Now some small engines call for it.Go figure!

buickanddeere · Aug 3, 2015

Shade tree , Steve and others of a similar theme are 100% correct

dr sportster · Aug 3, 2015

I alway figure I'm not going to outsmart some engineer that designed the motor. My owners manuals seem to compensate for summer / winter conditions. What the book tells me I don't change.

dhermesc · Aug 3, 2015

I couldn't imagine owning a car/pickup that I would run more than 6000 miles without changing the oil - let alone 25,000 miles - the US and the Koreans don;t build one that good yet. All it takes is a small coollant seep into the oil or an injector that's leaking extra gas into a cylinder and that 25,000 mile number is a work of fiction. At 25,000 miles you saved 5 oil changes (about $110) but your engine is toast.

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