Using 5W/20 oil while towing & hauling

#1

I own a 2004 Mazda Tribute (same as Ford Escape) with a 3.0 Ford Duratec V6. The owner’s manual and oil cap call for 5W/20 oil, which I have used since I bought the truck, with no problems so far at 53,000 miles. This weekend my father stopped by, a shadetree mechanic for decades, and seemed alarmed that I was using 5W/20 oil in the Mazda, especially since I tow a trailer with it (small trailer, less than 2000 lbs). He says that 5W/20 is basically “piss and water” and does not provide enough protection, especially when under load. What do you guys think?

#2

With all due respect to your Dad…He’s NOT an engineer. The engineers at Ford hopefully spent a good deal of time coming up with the correct oil weight for your SUV. I do believe they know a lot more about that engine then your dad does. If your overly concerned then switch to synthetic.

#3

Dad is from the old (really old) school, where “thicker is better.” Back when dinosaurs still roamed the earth he may have been correct, but he’s wrong now, and he should move into the twenty-first century with the rest of us.

The engineers who designed and built the engine specified 5W/20 oil for ALL conditions, and that’s what you should use, unless the owner’s manual states otherwise.

All dads have some bad habit that just won’t die. My dad, in his 80s, still slams doors, trunk lids, and hoods when closing them, thinking they are more securely closed that way. Drives me crazy when he does it to my car, but he won’t change.

#4

5w20 is mainly spec’ed for (slightly) better mileage and emmissions. 5w20 typically has a synthetic component (blend) in order to keep its properties and in those respects is slightly better than conventional oil.

Check the manual for specifics under severe usage.

#5

I have an older friend who was a mechanic, he’s also in his 80s . . . still pumps the gas before starting the car and also “gives it a shot of gas” just before shutting it off. With a new truck . . . but if it makes him happy, whatever. To the OP . . . use what the engineers call for . . . 5w20 is fine. Rocketman

#6

Just checked the owner’s manual. I saw nothing about using a different viscosity of oil, regardless of type of vehicle use. The manual has two service schedules, 1 & 2. Schedule 1 is to be used only if NONE of the following (very cold starts, short trips, towing, etc.) apply. Of course, my situation applies to Schedule 2 which calls for oil changes every 3,000 miles, transmission fluid and transfer case fluid changes every 30,000 miles.

My 4-stroke Yamaha snowmobile uses 0W/40. You should’ve seen his reaction to that!

#7

Those low viscosity numbers drive the old-timers crazy, but they make sure the oil gets where it needs to go quickly at cold start, and that’s mostly the point.

#8

The other point is…many newer engines are made with very very tight tolerances. During cold start…5w-20 and 5w-50 will flow the same. It’s when they heat up that there’s a problem. The oil becomes thicker and with the very tight tolerances the thicker oil needs to flow well. 5w-30 or 5w-40 may NOT be able to flow through the tighter passageways or channels.

#9

It’s when they heat up that there’s a problem. The oil becomes thicker

The way I read your post, you got that bass ackwards. The oil doesn’t get thicker as it heats up. That second number is related to how thin the oil will get when hot. More specifically, the 5W-40 will thin no more than a straight 40 weight would at the specified, high test temperature. At high temperature (operating), either of those oils will be thinner than when they are at their cold viscosity (5W).

As you noted, the 5W-30 will still be thinner than the 5W-40 at the high temperature.

#10

A few short years ago Ford switched virtually of their passenger vehicles to 5W-20 retroactively, including those that specified 5W-30. You would probably be fine with the -30 in hot weather towing a load. You will also be fine with -20. Note that the specification is probably for semisynthetic oil. You can get Motorcraft of the spec very inexpensively at Wally World.

#11

The way I read your post, you got that bass ackwards.

It depends on how you look at it…

When multi-viscosity oil heats the long chain molecules expand. So it won’t flow as well as the 5 weight oil.

#12

When looking at a multi-viscosity rating, like 5W-20, all you can determine is:

[list]At 0 degrees C, it will have the same pour point flow characteristics as a straight 5W oil.[/list]
[list]At 100 degrees C, it will have the same pour point flow characteristics as a straight 20W oil.[/list]

#13

I usually get my oil changed at the dealership. I assume that’s what they are using. When I change it myself, I use Castrol GTX 5W-20.

#14

When multi-viscosity oil heats the long chain molecules expand. So it won’t flow as well as the 5 weight oil.

That is completely false. All oils thin as they heat up. All the viscosity improvers do is slow the thinning process. A 40 weight oil at 200 deg F is lower viscosity than a 5 weight oil at 70 deg F. There are many sources you can use to verify this. One I see here regularly is here- http://www.bobistheoilguy.com/motoroil.html

A 5W-40 multi-vis oil will be thicker at 70 deg F than it will be at 200 deg F.

This is a commonly confused point. The second number relates to the viscosity at the high test temperature. It’s not saying that the oil will be as thick as a 40W oil at 70deg. It’s saying the viscosity will be the same as a 40W oil at 200 deg.

Anyway, hopefully the link I provided does a better job at explaining this point.

#15

All the viscosity improvers do is slow the thinning process. A 40 weight oil at 200 deg F is lower viscosity than a 5 weight oil at 70 deg F

The following websites completely disagree with you.

http://www.valvoline.com/carcare/articleviewer.asp?pg=ccr20040601ov

"It is the motor oil viscosity modifier additive that produces a thickening effect at high temperatures but is dormant at low temperatures. "

http://www.castrol.com/castrol/genericarticle.do?categoryId=8264018&contentId=7007302

“Such oils are called multigrade oils, for instance ?20 W40? shows thinness at low temperature and thickness at higher temperature.”

http://auto.indiamart.com/auto-consumables/engine-oil-its-viscosity.html