Synthetic Oil in V6 3.7L (2008 CX-9)

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08 CX9 AWD GT tow, all tech & aftermarket read dvd + moonroof
Hi,
So I used to run pure synthetic (Amsoil, sorry Mr. Mobil1?) in my Cougar and pimp Fiero... But then, I've leased cars for the past 9 years and they were lucky to get oil changes. Sidenote: Never buy a vehicle off lease! haha

Now I own a 2008 CX-9 and the sales rep told me specifically not to run pure synthetics in this engine, only blends.

Does anyone know that for sure? I know, I should search. I did search, a little, and here I am! (fu)

(sorry, that is just cool that you can use that emoticon, had to do it)

I see notes in another thread about the Wankel and synthetics, but does the 2008 CX-9 have the same issues as the other Mazda engine? Maybe this guy was just totally wrong.

I've only got the 11 miles on it right now, but when I do the first change I'll go to pure synthetics, if I can.

Thanks!
H
 
Mazda does not recommend full synthetics since they "haven't been tested in our engines." I run it in my MazdaSpeed 6 and plan on running it in our CX-9. Unless the manual spells it out for me, I'm going to go with synthetic. There is no reason not to.

I won't be extending the drain intervals past the 7,000 miles the manual calls for and I will be using used oil analysis to see how the oil is working out.
 
I have been running Mobile 1 in my CX-9 for 8,000 miles now and there haven't been any issues or leeking.
 
Do this: Whenever a salesperson hands you a general, sweeping (and incorrect) statement like that, make him tell you why. Synthetic oil does nothing but good things for new, traditional piston engine. The only Mazda that syn is a no-no for is the RX-8, as it's been traced back as an apex seal killer.

If he can give you a concrete reason (like it eats the seals that only Mazda uses on their engines), then by all means follow his advice. Otherwise, treat it like anything else a salesperson tells you, like 'break it in hard' or 'you've got me down so low I won't be getting a commission on this deal'.

I stopped listening to salespeople in 1997 when I was told not to put premium gas in my brand new Ranger because the higher octane eats holes in the plastic gas tanks. I told him if he had another way to make the MF stop pinging in hot weather, I was all ears.
 
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LOL, great stuff, thanks!

I had heard about the RX-8 so when he tossed that out I was like, "uh-huh..." and let it slide. I was still working on him to give me the free cargo nets, so I really didn't care.

Thanks!
H
 
My Mazda Dealer uses Castrol Syntec on all the Mazda CX-9's. And recommends an oil change every 10,000 Kilometers. I tried to tell them that according to the service book and Costa Rica's weather they should use 10w-30, instead of 5w-20,but they said factory recommends 5w-20.
 
syn oil

Using synthetic oil in a 3.7 motor is going to be just fine, it is 2008 you know. The issue for syn oil in mazda's comes from the rotary engine and its seals. For a street motor rotary, I can buy that argument. I have been building and racing the rotary engine for years and using synthetic for its high performance advantages, besides the motors always are clean on the inside from synthetic.

Use synthetic, the symbols on each brand are developed for automotive brands, just don't buy into the argument that you have to change oil every 3000 miles, synthetic allows longer drain intervals. I 6000 miles, change the filter (add a qt) and 6000 more before changing oil/filter on a diesel truck pulling 25000 lbs, if it is good for that, it is good for a car. (and that was 5w-30) I called Amsoil engineering department when I was first privy to the information, if it is good enough for a kenworth, good enough for me.

And they recommended even higher mileage intervals.

The US market wants to sell more oil, why do you think they have sold us the 3000 mile interval theory? in other countries it is more than 7500 miles, are the engine internals that different, no. Besides every manual states a longer interval.

D.
 
This tread made me think about this issue.
If you see my my posting: " Engine knock on CX-9 GT" you'll see that I had a problem with knocking that resembles to the valves and lifters.

When I took my brand new CX-9 from the dealer, the very next day I changed the oil and filter and used pure synthetic... Few days ago I changed the oil again and now I have regular Castrol 5-20. Immediately after, the noise was getting less intense, and 3 days after - completely disappeared.

Could that be related to the synthetic oil?
 
I've been using Mobil 1 5w-20 since 3000 miles. Have done 2 oil changes with it and have had 0 noise issues.

Synthetics usually quiet an engine...
 
not_too_shabby said:
Has anybody noticed a gas mileage improvement by switching to synthetic?
Click to expand...

Nope. No noticeable improvement to fuel economy moving to a light weight synthetic oil (5W-40 in this case). Engine does rev more willingly though. It is generally more quiet, with the exception of ticking noises noticeable only on cold starts. (This is not a problem though).

However, I have noticed a circa 2 litre/100km improvement to fuel economy by using 98RON fuel. Even at a 10c per litre premium over 91RON fuel here in Australia, it pays for itself and performance improves along with it. Ie: it is cheaper to run 98RON fuel than 91RON fuel, even though 98 costs more at the pump.

Cheers,
TTubrag.
 
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