Oil for 2021 Mazda CX-5 Skyactiv 2.5L Turbo

Pueblo county CO
CX-5 Sport 16.5 6M
A guy at a Chevy dealer told me they thought a synthetic blend or conventional ( they use a Quaker State product) has some benefits if you change it frequently. He said they really didn't recommend Mobil 1 except in Corvettes or the like. Maybe there are more natural solvents but I would think they would boil off. So you change it.
I normally use something like Mobil 1 or Pennzoil Synthetic but I've used a syn blend a couple of times in my other car as it gets little use so I change it around 3k miles anyway.
That oil was really dirty when I drained it.

Synthetic is supposed to be much better in cold weather. It coats the parts well.
It is also more stable in high temperatures than conventional oil.

I wonder exactly what brand if oil that dealer uses? Synthetic isn't that much more expensive at most stores. Maybe they get a real good deal on barrels of something.
Ottawa, Ontario
17 Mazda 6 GT
There's also the additional problem with most dealers in that they take the vehicle into the back and won't let you witness the actual oil change being performed.
They can tell you anything they want, and write whatever they want on the invoice, but you can never be 100% assured that what you asked for or what you paid for is actually what you got.
They can throw in crap bulk oil and bill it to you as a top grade synthetic brand.
Or they can say they did the work, bill you for it, but never actually do the change.
They can, and will, cheat. Bank on it.
I've been burned more than once in this scenario by dealers.
When I get oil changes, I go where I'm allowed to watch.


2020 CX-5 GTR
Thank you for all the helpful responses. You all make some valid points.

I change my oil and filter myself every 5K. I don't drive much so this will be 1x every 6-10 months.

I was at the dealer to buy oil filters for my first oil change. The parts guy knew I was doing the oil change myself, so maybe he is misinformed, but he had nothing to gain by recommending conventional oil only for the 2.5T as I was not buying oil from them. Wouldn't dealers want to sell you a synthetic oil change for higher profit?

He specifically said, "we only use conventional in the turbo engines, and you could use either synthetic or conventional in the non-turbo engines. In New England we recommend changing the oil every 5K." I was surprised to hear this as I already bought synthetic oil given this is a brand-new car.

I have no experience using synthetic oil as my previous cars I did not want to switch late in life as I have heard about potential problems with seals leaking etc.

Why would Mazda engineers not specify for synthetic oil in the owners manual if it prolonged the life of the engine or turbo?


Work In Progress..
'18 CX-9 Signature
Why would Mazda engineers not specify for synthetic oil in the owners manual if it prolonged the life of the engine or turbo?

I'm no Mazda engineer, but I would assume that in their testing, using conventional 5W-30 that meets certs and following the listed OCI resulted in ideal emissions/fuel economy ratings and allows the engine to last through the powertrain warranty period. I'm basing this partially on Mazda not changing the info in the owner's manual since the engine debuted, and partially on a business' natural desire to improve the bottom line.

I just use synthetic because I think it's better to use in a turbocharged engine, and because it doesn't cost much more than conventional 5W-30. In fact, I was at Costco yesterday, and a 2x4.73L pack of Kirkland Signature 5W-30 was $34.99 CAD. Personally I'd run the Costco synthetic over any conventional at that price.
Occupied Calif.
2019 CX 5 GT-R
The very best of the non-synthetic 5W-30 oils are quite good these days. You could probably do OK by using one of them in the 2.5T engine if you did more conventional 3000 mile oil changes, but given the popularity of synthetics and the frequent sale prices at places like Walmart, the difference in doing an oil change (if you do it yourself) with synthetic vs. conventional is about the same as a fast food lunch. You can extend your OCI's and you can sleep better at night.
I think it is just a matter of time until Mazda updates the recommendations in their owners manuals to synthetic. I imagine that the sales and therefore availability and lower costs of synthetics will continue to capture market share so there is no reason not to use a premium oil.
2018 CX-5 Sport
You can watch the test that PF does. I disagree with his choice of the winner between Castrol and Kendal because Castrol ran cooler on the bearing wear test and there was less evaporation in the heat test. PF put more weight on the flow test and the length of the scar that he measured on the bearing so he thought Kendal won.

2018 CX-5 Sport
As for conventional vs synthetic, the hotter the engine runs the more benefit synthetic oil gives. There isn't a debate. The dealer uses the cheaper oil to make more profits, not to help make your car last longer. The parts man lied. My snarky comment that was deleted meant that mechanics tend to lie more to women than men because mechanics tend to think that women know nothing about cars.