What'sthe Big Deal about 5W-20 vesus 5W30 Motor oil?

[FinanceDude]

I read that oil change places and dealers are pushing it because it helps meet the CAFE standards, that sounds like a bunch of BS to me...........

Plus, they charge MORE to put it in the car.........

Can't I just run plain ole 5W-30, like the old days??

 

[MasterBlaster]

Oil viscosity is a tradeoff. There is no definitive correct answer to the "optimum" oil.

5W-20 is definitely thinner than 5W-30. If you don't believe me then just pour a bottle of each into your engine. Many Ford engines (for example) call for the 5W-20 oil. The goal (I suppose) is to get oil lubrication quickly to those engine bearings just after startup. Thicker oils take longer to do this. The thicker oils however do protect better as the engine gets hot.


If you live in a warm climate then (per your Ford owners manual) you are allowed to use 5W-30.

 

[FinanceDude]

Oil viscosity is a tradeoff. There is no definitive correct answer to the "optimum" oil.

5W-20 is definitely thinner than 5W-30. If you don't believe me then just pour a bottle of each into your engine. Many Ford engines (for example) call for the 5W-20 oil. The goal (I suppose) is to get oil lubrication quickly to those engine bearings just after startup. Thicker oils take longer to do this. The thicker oils however do protect better as the engine gets hot.


If you live in a warm climate then (per your Ford owners manual) you are allowed to use 5W-30.

What about a colder climate like mine? I remember in the "old days", we switched between 10W30 and 5W30, depending on whether it was cold or warm........

 

[yakers]

Synthetic For Cold

For really cold places like Canada, Alaska and maybe upper US in winter synthetic oil is a good idea for easy starting. You do get some payback in lower fuel use due to lower resistance and some minor extention in oil change frequency (don't over do that, it may not break down but it still gets dirty over time). But the ability to start is great and get oil to the bearings quickly helps reduce wear too. Synthetic is good in hot weather too even though it is 'thin' it doesn't break down, but its not as compelling as in cold weather where there really is a difference in starting and quick pumping to the bearings.

 

[cute fuzzy bunny]

Some engine makers like the 20 weight oil because it gets lube to the upper engine a little faster.

Lots of "I put 5w30 in my car and nothing bad happened!" anecdotal stuff. Lets try that with a side by side test case for 150k miles and see how it goes. A couple of crankcases of mazola would probably be fine too.

I've pondered using 30w in the pilot, which calls for 20w oil...considering it peaks over 100 here for a couple of months a year. Most of what i've seen is that internal engine temperatures in modern motors really dont vary that much given a reasonable range of ambient temperatures.

My oil changers dont seem to charge extra for the 20w though.

A couple of oil manufacturers even sell a 5w30 thats actually a 5w20...they didnt wanna bother making two viscosities.

Now if you want a really interesting discussion, lets talk about a nice 0w20 vs a 5w20...

 

[samclem]

The thiner oils do give slightly better mileage. Still, I'm a little worried that what the manufacturers have to recommend in order to meet CAFE might not actually be better for my engine. It seems at least possible that 5W-30 provides superior protection for bearings and longer ring life than 5W-20 at the cost of maybe 0.25 MPG. If so, I'd rather use the heavier oil. OTOH, by advising the use of the thinner oil, the new vehicle manufacturer makes millions more dollars (by reaching CAFE standards with fewer rebates for high-efficiency vehicles) and the motor won't die until it is out of warranty. No problem for GM.

I think we'll need to see some real testing and be a little suspicious of the owners manual.

I wonder when cars will start to come stock with a pump to pre-lube the top end before the motor cranks. It would cost auto makers about 100 bucks to add one.