Dexos 5w20?

[john parker]

A little confused about the motor oil I should use in my 2013 Malibu LT with the 2.5. The manual and oil cap call for 5w20, GM "requires" Dexos approved, and most of what I find is Dexos 5w30. At the same time, am wondering if full synthetic would be a good idea. I think (but don't know for sure) that my dealer uses a semi-synthetic blend. Help? Thanks!

[Drunken Elvis]

Find some Dexos approved 5W20 and put it in your car. All dexos 5W20 will be synthetic or semi synthetic. Why are you confused?

[john parker]

Originally Posted by Drunken Elvis

Find some Dexos approved 5W20 and put it in your car. All dexos 5W20 will be synthetic or semi synthetic. Why are you confused?

Confused because GM calls for Dexos 5W20, and almost all the GM Dexos-approved oils are 5W30. Also a little confused as to why GM went from 5W30 to 5W20; used 5W30 for years.

[Mongoose]

Originally Posted by john parker

Confused because GM calls for Dexos 5W20, and almost all the GM Dexos-approved oils are 5W30. Also a little confused as to why GM went from 5W30 to 5W20; used 5W30 for years.

Closer tolerances require a thinner oil

[john parker]

Originally Posted by Mongoose

Closer tolerances require a thinner oil

Understand that! Now I am less confused! Ford went to 5W20 four or five years ago, if memory serves.

[DrivenDaily]

Originally Posted by Mongoose

Closer tolerances require a thinner oil

Nope.

Thinner oil slows the crankshaft less as it sloshes through the oil, which improves fuel efficiency.

Synthetic oil will pump more quickly during cold starts, which is where the majority of engine wear occurs.

Tighter tolerances during manufacture just mean the parts fit together better but the oil passages still need to have oil coursing through them. Lubrication comes from oil flow, not oil pressure.

[Mongoose]

Originally Posted by DrivenDaily

Nope.

Thinner oil slows the crankshaft less as it sloshes through the oil, which improves fuel efficiency.

Synthetic oil will pump more quickly during cold starts, which is where the majority of engine wear occurs.

Tighter tolerances during manufacture just mean the parts fit together better but the oil passages still need to have oil coursing through them. Lubrication comes from oil flow, not oil pressure.

I'll just say debateable and just 1 example

CAUTION TO SATURN OWNERS
I have actually experienced this one! If you stick 20w-50 oil in Saturns, the engine may never run again!!!! The tolerance is so tight on the hydraulic valve lifters that the heavier oil makes them "pump up" and keep the valves open all the time!
The motor will start up fine, but after it shuts off and cools down, it won't start again!
My customer had knocked a hole in her oil filter and limped home by adding oil she bought at a convenience store. The oil she bought was 20w-50, and although she made it home the car would not start again. I checked the compression, and it was zero on all cylinders. Upon disassembly, the head was OK! Then I read a service bulletin about the lifter issue. a set of new lifters and the Saturn ran fine again.

[nutcrunch]

The oil in your comparison is 20W50 (same oil I use in my air cooled motorcycle) which is much thicker than the 5W20 in question.
By the way, they still list 5W30 as recommended for our 2013 ECO.

[DrivenDaily]

So, what was the issue with the lifters? The oil apparently didn't cause the issue, the lifters did. Replaced 'em and it ran. I would even bet you that she could run on 20W-50 just fine now that the lifter issue has been corrected.

And what's debatable about the answer I gave? Tighter tolerances during manufacture don't turn into oil passages that are so small that thinner oil is needed. If 10W-40 is too thick to flow through the oiling system then I'd contend that 5W-20 is not much better. What those manufacturing improvements do is get you an engine that runs better for more miles and with less wear to break it in.

Case in point: How viscous is any oil at 20°F? Fossil-based oil has parafin in it that needs to warm up to flow; synthetic flows much more easily when cold. If most engine wear happens while driving down the road then that which happens at start-up is of little consequence. But since most of it happens during cold starts you would naturally want to protect your engine the best way you can by using synthetic or blended oils to assure the oil will flow as quickly as possible at that time.

For anyone who wants to learn more (like I did), a trip to Bob Is The Oil Guy with some reading is very eye-opening! I'm amazed at what I used to think was accurate until I went there and learned differently. Sure, some might say it's like drinking Kool-Aid, but ask them what they're drinking. (And maybe if they'll share some! )

I just have a measure of difficulty accepting your contention that today's tighter tolerances require thinner oil. And your example has too many other variables in it that are undefined to make it a plausible reason to buy into your statement.

[Opusnbill7]

Originally Posted by john parker

A little confused about the motor oil I should use in my 2013 Malibu LT with the 2.5. The manual and oil cap call for 5w20, GM "requires" Dexos approved, and most of what I find is Dexos 5w30. At the same time, am wondering if full synthetic would be a good idea. I think (but don't know for sure) that my dealer uses a semi-synthetic blend. Help? Thanks!

I think that all Dexos oils are going to be a semi-synthetic blend. I *know* that the Dexos oil used at Husker in Lincoln is a semi-synthetic. The synthetic they use is Mobil 1 and is also Dexos (like comes standard in the Cadillacs).

I just had my first oil change, and went with a full synthetic for peace of mind. I know that the semi-synthetic is supposed to be fine, but since I plan to change it only at the recommended interval, I personally feel better with it being full synthetic. Especially when you consider the cold starts on days like we've had the last few weeks.

I can't speak to whether they put in 5w20 or 5w30, but I'm sure either will be fine. From the things I've read it's mostly a fuel economy issue (one of they saves like 0.25 mpg or something like that for CAFE).