Dealer recommended conventional oil?

I had my first change Today on my 2019 CX-9 and they put conventional oil in it and said it was better for the turbo. This blew my mind and sounded completely false. Can’t find anything in the manual either way. I have been using synthetic in all my cars cars for years and I was dumbfounded. Any intel out there on this??

Sorry guys - I found a rather complete older thread on this. Sounds like I can put in what I like - Mazda doesn’t recommend either. Sounds like a dealer thing. Do my own oils anyhow, now that my free one is over, I go synthetic thank you.
 
Last edited:
Dealership service writers have no training in lubricants. They sell what they're told to sell, or they sell what they have the biggest margin on, or they sell based on old shadetree mechanic myths. Trust the owner's manual. Conventional oil is OK. Synthetic is superior for the very cold, the very hot, and lower rate of oxidation (so longer useful life). I use syn in my turbocharged engine.
 
5w30. Oil is oil just like gas is gas. Putting Chevron 91 doesn't mean your car will better than Arco 91.
That’s not true. You have different base stocks in oil and a bunch of different additives that make up different manufacturers. Some flash at different temperatures and some are more resistant to mixing with gas (best suited for DI Engines).


Gas you have top tier which has a certain certification of additives and a level which it has to be to have the certification.

 
"5w30. Oil is oil "

I'm with Brett. All that said, every update to the API service categories (Currently tops at SN+), the ILSAC specs (GF-5), and the manufacturer specific specs (like GM's Dexos) requires better oil so the products that meet the specs are better than previous versions. That's just to meet the spec. Some oils exceed the spec. I use either Castrol full syn or Mobil 1 oils.

New oils to meet the newest specs will soon be on the market. API SP and ILSAC GF-6A (for engines like ours). These will be superior to the older specs and fully backward compatible.

There are bad oils on the market, mainly on convenience store shelves. They either meet an obsolete spec that is not suitable for our engines, API SA up to SM, or the label is OK but the oil is garbage.
Petroleum Quality Institute of America
Here's an example--REV 360 5W-30:
"The results of the tests conducted on this sample do NOT meet the SAE J300 specifications for the SAE Viscosity Grade listed on the product label, and are NOT consistent with the listed API Service Category. The Low-Temperature Cranking Viscosity is nearly six times higher than the maximum viscosity specification for this SAE grade. The Kinematic Viscosity @ 100°C could not be determined due to the presence of water, but is also very likely higher than the specification based on the very high viscosities @ 40°C and -30°C. In addition, the phosphorus content is over five times the maximum level required by the referenced API specification which could cause damage to catalytic converters. Furthermore, the organometallic additive levels in this sample are exceedingly high, potentially leading to excessive piston deposits, and the silicon results indicate the product may be contaminated with abrasive material.

"Use of this product in modern automobile engines will likely cause harm to the engine."
 
Last edited:
Anyone using the Castrol Edge European Formula (0w40, previouly 0w30)? That oil has always seemed to be a fairly popular choice in previous cars I've owned (not just the German makes); could have just been sort of a cult following/novelty thing I suppose.
 
I'd use an xW-40 oil only during blistering hot summers...Phoenix, etc. Castrol Edge is fine oil, as are many others, but the viscosity needs to match the engineers' recommendations and the operating temperature. In the same vein, I'd use a 0W-20 during frigid winters (and electric engine, transmission, & battery heaters).
 
I had my first change Today on my 2019 CX-9 and they put conventional oil in it and said it was better for the turbo. This blew my mind and sounded completely false. Can’t find anything in the manual either way. I have been using synthetic in all my cars cars for years and I was dumbfounded. Any intel out there on this??

Sorry guys - I found a rather complete older thread on this. Sounds like I can put in what I like - Mazda doesn’t recommend either. Sounds like a dealer thing. Do my own oils anyhow, now that my free one is over, I go synthetic thank you.
Regular oil will have to change more often..3k-5k. Syn can last much longer. So which do you think makes them more money? Dealers make money on aftersales services.
 
Any sentence that starts with "Dealer service said..." is sure to end in complete BS or an outright lie. They are commissioned sales people disguised as advisors; and sadly they have managed to become the worst of the worst at the dealership.
 
Gott'a watch 'em like a hawk. If they don't sell service items, they get fired. A couple of things to do--
  • Follow your owner's manual. The car maker puts their warranty money behind the recommendations there.
  • Be sure any problems are fully described on the repair order. Don't accept the service writer's guess about how to fix the problem when the tech doesn't know the problem. If they didn't fix the problem written on the repair order, don't pay. You didn't get what you asked them to do.
  • Inspect the result. You get what you inspect, not what you expect.
 
Funny, when I asked my dealer to put in synthetic oil they said that's the only thing they put in for the CX-9, wether I ask for it or not.

Based on the manual conventional oil is fine. But as mentioned above by PTGuy, synthetic is always a better oil. So it is your choice.
 
Just had the same experience Jeff described at the dealer. Brought my ‘16 CX-9 in for my last dealer service while it’s still under the last 500 mi of power train warranty yesterday. I was very surprised to hear the experienced service writer recommend conventional over the full synth I’ve been using since the first oil change. He said Mazda recommends this as this turbo engine is known to burn a bit of oil 🤔. He also told me that old thought process that once you go synthetic you have to stay with it does not apply anymore.

I took his advice and let them use conventional oil. I tend to agree with what Maolo said. I figure saving $10 on oil puts me back in for service at a shorter interval and that’s the win for the dealer. I planned to have my local mechanic take care of service from this point out anyway.

Upon further consideration I wish I stuck with synthetic. Our engines run super hot.
 
Back