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I went to my dealer (Autobarn Mazda) for my 1st oil change. I noticed that they put 5w-20 Castrol GTX regular motor oil. The owners manual states 5w-30. The oil filler cap on the car says 5w-20. I called another dealer and they say 5w-20 regular oil. Folks on this board swear by "synthetic" oil with different grade, for example: Mobil 1 0w-40. Needless to say, I'm confused.

Scan from the owners manual attached...
[attachmentid=16034]

What is the correct grade oil for this car? Does the grade change if you go with Synthetic?
Please advise...
 

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there are two recommended grades mentioned in the paperwork you get from mazda. 5w-30 is mentioned in the manual, but if you look at the quick reference guide that comes with the manual you will see that it also recommends 5w - 20. I'm planning on going with 5w-30 for added protection during the summer and 5w-20 for the winter.
 

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there are two recommended grades mentioned in the paperwork you get from mazda. 5w-30 is mentioned in the manual, but if you look at the quick reference guide that comes with the manual you will see that it also recommends 5w - 20. I'm planning on going with 5w-30 for added protection during the summer and 5w-20 for the winter.
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My dealer does the exact same thing, I asked them why and they said they're instructed to use 5w-20 during the winter and 5w-30 in the summer.
 

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I went to my dealer (Autobarn Mazda) for my 1st oil change. I noticed that they put 5w-20 Castrol GTX regular motor oil. The owners manual states 5w-30. The oil filler cap on the car says 5w-20. I called another dealer and they say 5w-20 regular oil. Folks on this board swear by "synthetic" oil with different grade, for example: Mobil 1 0w-40. Needless to say, I'm confused.

Scan from the owners manual attached...
[attachmentid=16034]

What is the correct grade oil for this car? Does the grade change if you go with Synthetic?
Please advise...
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you'll be fine, just like the other 2 users said
 

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Maybe I'm wrong, but shouldn't the oil in the Speed6 be at least synthetic blend? 5W-20 is fine, up there in Chicago during the winter and fall it's probably better.
 

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Maybe I'm wrong, but shouldn't the oil in the Speed6 be at least synthetic blend? 5W-20 is fine, up there in Chicago during the winter and fall it's probably better.
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Actually, I believe you are right. I think the dealer/factory uses a semi-synthetic Castrol blend.
 

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You dont really want to change to synthetic till after about 10k anyways. That way you let the piston rings totally seat and dont cause cylinder glazing.
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I am at 18,000 and I just changed mine to synthetic.
Damn all you and your low miles! :)
 

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Your rings better seat before 1000 miles otherwise you would have a huge amount of blow by and alot of oil loss. New cars have much tighter tolerances and there are MANY that come with synthetic right from the factory( Corvette, Porsche, AMG, ect.) The last 5 cars that I have bought have been changed over to Mobil 1 at around 1000 miles. Never had an engine falure, none used any oil to speak of, and my Contour SVT is over 150,000 miles and still strong as day one.

I can't understand why you would wait to use something BETTER?
 

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Your rings better seat before 1000 miles otherwise you would have a huge amount of blow by and alot of oil loss. New cars have much tighter tolerances and there are MANY that come with synthetic right from the factory( Corvette, Porsche, AMG, ect.) The last 5 cars that I have bought have been changed over to Mobil 1 at around 1000 miles. Never had an engine falure, none used any oil to speak of, and my Contour SVT is over 150,000 miles and still strong as day one.

I can't understand why you would wait to use something BETTER?
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+1
 

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Well some of the oil companies state the following:
One of the myths surrounding synthetic oils is that new engines require a break-in period with conventional oil. The fact is, current engine manufacturing technology does not require this break-in period. As indicated by the decisions of the engineers who design the high-performance cars listed above, Mobil 1 can be used starting the day you drive the car off the showroom floor.

Not suprising since they sell it. But if you do a search online and read about the switch from one to another you will see quite a few reasons why it is good to wait.
 
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