[mooncancook]

I started with Mobil 1 0W-20, then they are no longer available so I switched to 5W-20. Now my local Walmart stocks both 0w-20 and 5w-20. Which is better?

 

[Mazda Gremlyn]

Both are fine for you to use, but knowing where you live might help the advice given as the lighter weight oil's lubrication ability can vary in different climates. So... put your location in your profile

 

[mooncancook]

I mostly drive around NorCal and bay area.

 

[posttosh]

I started with Mobil 1 0W-20, then they are no longer available so I switched to 5W-20. Now my local Walmart stocks both 0w-20 and 5w-20. Which is better?
[/b]

Hoo-bouy!

You need to spend a week reading bobistheoilguy.com (BITOG), where that subject is the topic of continuing, extended, technical, and heated debate all the time.

I have done my own homework there, and I have been converted -- sort of -- to "GC": the oil with its own cult. See below.

There are 13,000 people -- many of them very knowledgeable professionals -- posting their own strongly held opinions there, and it is a task to separate the wheat from the chaff. But I can tell you my impression of their areas of consensus.

1. Follow the vehicle manufacturer's recommendation and you cannot go wrong. For the Mazda6, that means that you run 5W-20 whether you are in Alaska or Panama, summer and winter.

2. If you do not follow the manufacturer's recommendation, the best reason not to is that you have joined the GC cult.

3. If your oil change interval (OCI) is every 3,000 miles, then you can get away with using just about any "name brand" oil; they'll all do o.k.

4. If your OCI exceeds 7,500 miles, which is the OCI in the Mazda6 manual, you are better off with a synthetic oil than with a "dino" oil.

5. Not all 5W-20 oils are the same; some are better than others. Among oils that are not full synthetics, the Motorcraft 5W-20 "synthetic blend" (probably less than one-quarter synthetic, blended with mostly dino) that came as the original fill on your new Mazda6 is considered very, very good -- perhaps the best oil you can buy that is not a full synthetic. Ford, working hand in hand with Conoco, developed the oil to be its "world" oil for all its passenger vehicles (but it has not quite reached Volvo yet). It is also sold separately under a Conoco label. You can buy Motorcraft 5W-20 synthetic blend at any Ford dealer or on-line through amazon.com, and it is very competitively priced.

6. GC (German Castrol: it says "Castrol Syntec" on the bottle, and "made inGermany" on the back) is different from all other Castrol Syntec oils. In the U.S., it comes in only one weight: 0W-30, and is sold at retail by only one store: the AutoZone chain. At very low temperatures, it flows better than Motorcraft 5W-20 synthetic blend, and at very high temperatures, it is a "thick 30" oil, actually behaving more like a 40 weight oil. It probably will protect your engine as well as any oil made, but will not yield as good gas mileage numbers as you will get with Motorcraft 5W-20.

7. Ain't no flies on Mobil1 (or M1 as it is called on BITOG forums) -- everybody agrees it is pretty good -- but there is very strong disagreement whether it is worth the price. Is it better than the Motorcraft synthetic blend? Perhaps, but not certainly, and it is much more expensive than the Motorcraft. It costs as much as GC: is it as good as GC? The GC cultists will hear none of that.

8. Oil filters are another question altogether.

 

[Jax6S]

I consider myself a GC cultist! Here's the thread incase you're interested.

 

[Betelgeuse]

I've used 0w-20 in the past and have had no issues whatsoever. Now I've been using mobil 5w 20 full synth and will stick with it till I get rid of the car. I plan on 6500-7000 oil change intervals though.

I've also heard good things about Motorcraft on bobistheoilguy.com. With regards to filters, the general consensus is that the Motorcraft fl - series (like our stock fl-820s) are excellent. There's a guy over there with the nickname 'filter man' that could pretty much answer any question regarding filters down to what each letter stamped on the outer case means. Those guys are serious gear heads for sure.

 

[Awong124]

If you live in California, 5W-20 would probably be better since it doesn't get very cold, but both will probably work fine.

 

[chikoo]

SAE50

 

[timk]

there are oil-police out there, for sure. follow the owners manual and use a good name brand oil, and you are fine. these words might be herasy to some, but all the independent info backs it up.

 

[SCORPION6]

Hoo-bouy!

You need to spend a week reading bobistheoilguy.com (BITOG), where that subject is the topic of continuing, extended, technical, and heated debate all the time.

1. Follow the vehicle manufacturer's recommendation and you cannot go wrong. For the Mazda6, that means that you run 5W-20 whether you are in Alaska or Panama, summer and winter.


Hey here in Panama, Mazda Dealer and the Mazda Manual recomend 10W-30. And my 6 is a 2.0

http://www.carbibles.com/engineoil_bible.html

http://www.carbibles.com/viscosity.html

 

[mbrogz3000]

I'm finally back to using 0w-20. It no longer states on the bottle that its for use with engines that require 5w-20, but it states it on Mobil1's website. Either of the Mobil1 oils are great, since you can run it longer without worrying about it breaking down. The only thing you have to still watch is the level, since these 3.0Ls gradually burn oil.

 

[Ericzoom]

I was using M1 0w20, but switched to 5w20 because Pepboys didn't have it. I figured for 3.99 a qt. it was worth it.
My 6 V-6 doesn't burn any oil between changes.

 

[chikoo]

my v6 burns about 1/2-1 qt in 3000 miles.
which is actually good as it gives me a chance to put in a fresh quart of oil at 3000 miles and make my tbn numbers go back up!

 

[DennisW]

SAE50 [/b]

Brilliant

 

[zoomnbyu]

Motorcraft 5w20 Syn-Blend :yesnod: - I do 5K mile intervals and have used it since my 1st oil service along with BG MOA oil additive.

 

[ToyFigure]

I was having the same concerns too because I was using Mobile 1 10W-30 and later switched to Castrol 5W-20.

I have a strange question, can you mix motor oils up? I mean since my 6s takes 6 quarts of oil, can I use 3 quarts of 5W-20 and 3 quarts of 10W-20 (same brand, full syn) in an oil change? Just curious

 

[zoomnbyu]

I have a strange question, can you mix motor oils up? I mean since my 6s takes 6 quarts of oil, can I use 3 quarts of 5W-20 and 3 quarts of 10W-20 (same brand, full syn) in an oil change? Just curious
[/b]

NOT a great idea.

 

[posttosh]

I was having the same concerns too because I was using Mobile 1 10W-30 and later switched to Castrol 5W-20.

I have a strange question, can you mix motor oils up? I mean since my 6s takes 6 quarts of oil, can I use 3 quarts of 5W-20 and 3 quarts of 10W-20 (same brand, full syn) in an oil change? Just curious
[/b]

See BobIsTheOilGuy thread. Executive summary: yes.

 

[Jax6S]

I don't think it's a good idea. I mean, why do you want to do that? The viscosity of the oil will be screwed up.

I can understand if you want to mix the same weight but different brand to compensate for lack of additive in a particular oil.