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I've been avoiding writing about this subject for some time now; probably for the last few years since 0w20 was adopted by Honda.

I really didn't think that many people would be confused by the oil options, nor that many would deviate from the OEM oil cap spec.


...however

There have now been quite a few posts on which engine oils to use and when.


If your engine is not leaking or burning
Use the viscosity of oil it was originally shipped with

So if it says 5w20 on the cap use 5w20, if it says 0w20 use 0w20.


Many zero weight engine oils offer lower oil film rates and therefore run higher risks of wearing out engine components (bearings, rings, camshafts). Though this is a risk the zero weights operate within the safe film zone.

There are a few "racing oil" zero weights that test high in film rate and shockingly Quaker State 0w20 ultimate tested very, very well... and that brand in general is not thought of as a high end engine oil.

But, most of the zero weight non-racing/non-euro formulas test quite a bit lower than their 5w20 and 5w30 counterparts across a brand.

Source: https://540ratblog.wordpress.com/201...-test-ranking/

The other issue which is of larger concern is oil viscosity.

The viscosity of an engine oil is commonly referred to as "thickness," but this should really be understood as the ability to bridge a gap in the engine tolerances.

There are gaps between the crankshaft bearings and the crankshaft for example. When the engine is new the gaps are small so a low viscosity oil will keep everything happy. However when the engine wears these gaps get larger and a thicker oil is often used to quiet worn parts or additives that increase viscosity and film. Like this video shows.




The smaller the number before the "W" in an oil viscosity the higher rate of flow it will have when at a colder temperature. Like this video shows.


So now we can see that for a given temperature 0w20 will be thinner than 5w20, or, it will have a harder time covering the gap between the bearings and the components.

So if your engine was designed for a larger gap coverage (5w20), running an oil which will be thinner and cover the gaps less (0w20), is not a good idea.


If your engine is burning or leaking

Run one of the options below, they are listed from least extreme leaking to most. (keep in mind the higher the viscosity/film, the lower mpg and power).

For (5w20 OEM spec. vehicles)

-light burn = 5w20 plus top up of 0.5l per oil change
-5/20 high mileage
-5/20 high mileage plus thickening additive (I like lucas HD for burning and Lucas stop leak for leaks, I've run them in thousands of cars)
-10w30
-10w30 high milage
-extreme burn/leak/knock 10w30 high mileage plus additive.

 
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stuck

 
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Thanks man, took a while to compile. =D

 
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Bump, since there are a few people asking.

 
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I got the car from my daughter while mine is been fixed
I believe she used to change oil at Honda
As I got it, I started doing it myself also using 5W20, according to the info on the Oil Cap, with Mobil1 Filter
I switch to only Honda fluids and Filters (car is 17ys old)
Last time I bought Oil at Honda (the price is shameful), they having all the specification of the car (Civic EX 2006 - Automatic, etc), they gave me 0W20 (maybe by mistake, I do not know - my mistake also, I did not checked before getting home, and only 2 days later)
Anyway, I check in the web everywhere, and got to the conclusion that, for the cold weather in the Winter Tri-State Area, it could be used (remember, specification is 5W20, and warranty can be killed if your motor goes byebye, and they checked that you were using the wrong oil)
I am going for changing the oil again, but will be back to the 5W20 (winter is over)
I believe that the confusion about oil, has to do with the fact that even when you inquire about the oil for the civic at Honda (even my old one), you get the info that "Your Honda Civic uses synthetic 0W-20 rated oil".
So, why I can only find that the oil for the car is now Synt 0W20 when the Oil Cap clear states that it is 5W20?

 
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Honda added 0w-20 as an acceptable viscosity to most models that were currently using 5w-20. I don't know when it happened but it was after your car was built which is why the cap says 5w-20. Look at the chart at the link below. 0w-20 is recommended for your Civic, 5w-20 is also okay to use.

https://www.bernardiparts.com/honda/....aspx#skutable