Oil viscosity

in the 40/50’s I used a straight detergent weight oil depending upon the seasons in Wisconsin. Switched to 10/40 in the 60’ to the 80’s. Now use a 10/30 all year around.driving is usually the serve type all the years --stop & start primarly. i now reside in a hot area of the country, normal 80/95+ tempuratueres 8 months of the year. 0/20 or 5/20 now is recommended by the shop. What impact does weather play in your viscosity selection for oil usage? if any?

I live in a cold area of the country so I use a 5W-30 oil. The 5W of the oil viscosity is the Winter weight. So when the engine is started cold in cold temperatures the oil is thin enough to lubricate the engine. Once the engine reaches operating temperature the oil viscosity is like that of a 30 weight.

Follow what the vehicle manufacturer recommends. After all, they’re the ones who did all the research to determine what oil viscosity is best for the engine.


Many car makers now recommend the 0-20 grade because it gives the best fuel mileage with is very important to them. Having their engines last forever is NOT important to them. Just so long as they last say 100K miles, that’s good enough…

Today, engines are built by robotic machines that can maintain VERY close tolerances. Special alloys are used in critical areas…So now the low-viscosity lubricants can be used, delivering high fuel mileage while providing adequate lubrication and engine life…

If the truth be known, even the old engines will run happily on #20 motor oil summer and winter…

Also, a bit of trivia, there are TWO GRADES #20 motor oil…20 and 20W. They are NOT the same…20W is winter rated, it will still flow at zero degrees F. #20 oil will not and is not suitable for winter use…At 200 degrees F. both these oils meet the 20 weight requirements…

I would not use 5W20 or 0W20 in an older car. Even if they lubricate adequately, older engines are a lot “looser”, and your car will likely use oil.

A few years back I had a Ford Explorer on a project and the manual called for 5W20 for one engine and 5W30 for another engine in the same vehicle. The 5W30 was for the older enine, the V8, I believe.

Last year I rented a new Toyota Matrix, and it called for 5W20 mineral or 0W20 synthetic. It also said that using 1 quart every 750 miles was “normal” oil consumption!!!.

Caddyman is right that these thin oils are CAFE driven to get the miles per gallon up. I have worked in hot countries and the normal oil in the tropics is 20W50!!! So, if I had a new car in a hot area, I would use 5W30 minimum and switch to 0W30 full synthetic for cold winters. Vokswagens require 0W40 synthetic!!

The only automotive engine I have seen damaged by “lubrication failure” was when there was NO oil in the engine…If these engines are supplied with clean motor oil at the proper pressure, lubrication failure is not an issue…

I firmly believe that most engine wear occurs during those first few seconds during a cold start-up when there is NO oil pressure and virtually no lubrication…The 0-20 grade gets moving significantly faster than heavier grades…No one can deny that today’s engines last MUCH longer than those of 20 years ago…

Until 1965 when I bought a 1965 Rambler, I always used straight weight oil–30 weight in the summer, 20W-20 in the fall and spring, and 10 weight in the winter. I changed oil every 2000 miles. The manual for the Rambler recommended 10W-30 year round with oil and filter changes every 4000 miles. I followed that recommendation and the engine outlasted the car. Later vehicles I have owned called for 5W-30 and 5000-7500 mile oil changes. The 2011 Toyota Sienna calls for 0W-20 full synthetic oil and 10,000 mile oil changes. Times change–oils have improved and engines certainly have improved.

The only place where use a straight weight 30 oil is in my 4 stroke lawnmower. I have seen two lawnmower engines blow a connecting rod bearing when the owner used 10W-30.

I agree…nothing beats specializing whether it be your tires or oil. Unfortunately, with longer oil change intervals, using one Multi viscosity oil year round, especially in cars driven in multiclimate Travel situations , is the norm. You can no longer specialize our oil like a mower…mine doesn’t ride and it never leaves home.

dagosa–I have an 8 hp generator with a 4 stroke air cooled engine. If the engine is to be used only in hot weather, 30 weight oil is specified. However, if the generator is to be used year round, 5W-30 synthetic oil is specified. My mower doesn’t ride and either and doesn’t leave home. Since I only mow in warm weather, the straight 30 weight is sufficent.

At least the way non contractors like us use a generator, I’m more concerned with starting then longevity. Next year I’m using a synthetic. My only 4strokes other then cars are a couple of outboards which get the exact manual treatment recomended. Too much money per pound in marine equipment to do otherwise.
I’m milking my 16 year old two stroke lawn mower motor as long as I can being that it’s light and I mow the side of a mountain. If you could recomend a cheap reliable replacement for hills which I 'm sure I would need soon, I would be a happy camper.

I used to live in Colorado at 6500 feet and it was quite cold there in winter. Now I live in coastal Calif, and it often never freezes even once during the winter. The summer’s are usually not very hot either, but occassionally w/freak weather conditions the summer temps can go into the 110’s. Both in cold Colorado and here in warmewr Calif I’ve always used either 10-30 or 10-40 and never had any problem w/either. I tend to use the 10-40 if I change the oil in the summer and the 10-30 for oil changes in the winter, but truth be told I’m not consistent, just what I have in the garage that day. I always use Penzoil, but I’m not sure the brand makes much of a difference or not.

The extreme light weight oils being recommended to you seem a little excessive and might lead to early engine wear. But it may be that in your climate that’s the best compromise. Suggest to ask your neighbors, fellow church goers, co-workers, etc and get an idea what most other folks are using first.

The middle path is often the best.

I remain skeptical of the 0W-XX oils in flat tappet engines, especially the air cooled type. My 4-stroke yard equipment gets 10W-40 oil but it rarely gets started when the temperature is below 75*.

“I’m milking my 16 year old two stroke lawn mower motor as long as I can being that it’s light and I mow the side of a mountain. If you could recomend a cheap reliable replacement for hills which I 'm sure I would need soon, I would be a happy camper”.
Dagosa–I feel your pain. I prefer a two stroke engine on a push type lawnmower, but these mowers are no longer available. I think you have three choices: 1) buy a battery powered electric mower: 2) continue to conserve your present mower. I remember a Chevrolet ad on the back of a “Time” magazine my parents saved when WW II ended. The ad mentioned that while new Chevrolets were being produced, the supply would not keep up the demand and one should continue to conserve the present car; 3) watch for ads selling used 2 stroke mowers and buy a couple of them. My brother has a steep incline he has to mow and has two or three used 2 stroke Lawnboy mowers. Parts are expensive. I think he had to pay over $100 for a new ignition module for one of the mowers. He didn’t pay that much for the mower.

Put in exactly what your owners manual recomends. The people building these cars know better than anyone what they need. Especially when it comes to motor oil the world is full of old wives tales and weird anecdotes that are all crap.

Tri…keeping a couple available will be a hard sell both money and space wise. My garage is filled with gas powered tools devoted to cutting along with all the toys a retired “playing boy” could muster. I like the idea of going to electric but…it has to be self propelled and they aren’t there yet? I like looking for used too. . Brought my last pusher with me to the mountain from a flat residential area…air lasted two mows before my back gave out and I secured a self propelled. Next it’s goats. They make very expensive 4 stokes with oil pumps to handle the inclines…last resort. Did I mention it must be rwd, like cars need to handle the hills.

My riding mower has never had anything but straight 30 weight Pennzoil in it and it is still going strong. It is a 1978 I-H cub 85. Anyone know where I can get a bagger for it?

My new Toyota Camry uses 0W20 and the manual says 1 quart per 600 miles is acceptable.

Weather isn’t really an issue, like it used to be. Modern motors are designed to run with thinner weights of oil. The thinner oil reduces friction and helps get more mpg. Today’s motors also run hotter which improves emissions out the tailpipe. So, all motors are running at the same temp once they are warmed up, Arizona or Wisconsin doesn’t make a difference.

The difference is what is the temperature at start up when the motor is cold. Here there is big difference depending on location. Yet, 5W or 0W oils are recommended now for cars in both climates. 5W-20 is fine for cold starts. If you lived in very frigid areas at -20 degrees 0W-20 would be better than 5W-20. So, in modern engines the difference is only at very extreme temps and even then only upon cold starts.

Many car makers now recommend the 0-20 grade because it gives the best fuel mileage with is very important to them. Having their engines last forever is NOT important to them. Just so long as they last say 100K miles, that’s good enough…

And where did you pull that from??? Maybe the bombs you buy…but I know many people running on 0w/20 with will over 150k miles and not one engine problem what-so-ever…A couple are GM’s…at least one Ford…and a few Toyota’s…

I use 0W30 in the winter, 0W40 in the summer. The higher weight oil is recommended in temps above 100F for many turbo vehicles.

This discussion will likely go on a long time. Mike; from the manufacturer’s point of view, you want an oil that gives maximum gas mileage while giving adequate engine life under nromal driving. The new Toyota advice in their manuals that 1 quart in 600-750 miles is “acceptable” is the result of these new thin oils either slipping past the rings or just leaking out. This is in spite of better manufacturing techniques, as pointed out by several posters.

OP’s and my own driving would not cause excessive wear while using 5W20 or 0W20 synthetic. However, if OP loads his car up for vacation, and pulls a camper across Death Valley in July, he may cause a great deal of engine wear with those thin oils. That’s why German cars have a severe oil spec and 0W40 synthetic is now specified for VWs. Gerrman cars are often driven at 100 mph for hours on end.

A late friend, who was an oil consultant, coached a Corvette racing team to victory with 0W20 oil. The goal here was to WIN a 500 miles race; engine wear and oil consumption, as well as fuel consumption, was not an issue.

Sjonnie seems to have the right idea. The 0W40 is great in even the hotttest summers.

The new Toyota advice in their manuals that 1 quart in 600-750 miles is “acceptable”

That’s NOTHING NEW…Manufacturers have been saying that LONG BEFORE 0w-20 was ever invented.

And the only thing I’m questioning is Caddyman’s statement that engines aren’t lasting a long time.

0W-20 MAY be slipping past the rings…but is it harmful to the engine??? And does it decrease the longevity of the engine??

I remember using 10W-40 and then 5w-30 became the standard…and everyone was saying “5w-30 is too thin…and won’t protect the engine from wear. You’ll start seeing engine failures at 100k miles.”

Well that never happened. And so far I’m hearing about engines not lasting any longer.