The site you are referring to is specific to Mobil1 (synth) and mixing dino with mobil1 (synth) which are non-dino oils.

The post in question is mixing valvoline (dino) and the stock 8 oil (dino)

 

If stock fill is brand X, and then you go to Valvoline, you think there's going to be a problem?

Any car, when you change the oil, there is still residual oil left in there!

If this was the case, there would be blown engines everywhere, and serious warnings on labels of oil!!!!

To appease you, I have emailed both Castrol and Valvoline about this issue.

I'll post up when I get a response back from the source!

 

Here's a response back from valvoline:

 

Man, syntrix, that was satisfying! "chemical reaction..." indeed. *guffaw*

 

Hahah!

Now think about all that oil left in the oil cooler when you change out the oil.

What do you suppose the factory fill is? Better be whatever brand you choose

I am still waiting for castrol to come back with an answer

 

ill never buy castrol after they were able to beat a a mobil suit against them for calling their syntec "synthetic" even though it comes from a base stock. They were able to find a loophole that allowed the "synthetic" term because they changed enough things to the oil. Look it up on google. ive always used mobil one until now in the 8. ill stick with penzoil and pure one oil filters (if they make them for the 8 yet)

 

Here's some important info found on valvoline website:

"A typical modern car may require a multi-viscosity oil rated at 5W-20, a number that would have been unthinkable a short time ago. But that relatively thinner oil is designed to work in conjunction with the tight engine clearances and provide adequate lubrication from a cold start-up in the winter in Minnesota to a blistering drive across the desert near Phoenix in the summer. If you use a heavier oil because you think it's "better," you'll not only be wrong, you may cause your engine some damage since it won't be properly lubricated during start-up and in cooler weather. Furthermore, if you decide that if a range of 5W-20 is good, then 5W-30 must be better because it's a wider range, you'll also be wrong, since the things done to give that oil the wider range may not necessarily be what your engine needs.

The best oil for your car is what the manufacturer recommends. Use the correct viscosity as outlined in your owner's manual, purchase quality oil from a reputable company, change it regularly, and take good care of your car. "


Would you still put anything other than 5W-20 in your 8???

 

The answer depends on where you live - in the UK, Europe, Australia, in fact anywhere outside of North America, Mazda's recommended oil viscosity is 5W30! I would expect them to happily use 5W30 instead of 5W20. Also, based on that, I would not expect any problems at all using 5W30 in North America either.

Regards,
Gordon

 

Check this web site: www.bobistheoilguy.com There is a wealth of information there. The forums are particularly informative.
They generally do not rate Valvoline as a top oil.

Bear in mind that all brands of oil are constantly being changed. What this can mean is that an oil that was one of the best formulations five years ago may only be an average oil today. For example, I have always heard very bad things about Penzoil in the past - usually from mechanics. Today, it is apparently one of the best non-synthetic oils on the market.

That being said, probably any modern oil would prabably be adequate and not harm your engine - in the correct viscosity.

Personally I have used the original synthetic oil - and I believe the best - in all my other vehicles. In my RX-8, I use the Motorcraft 5w-20 oil. It is a synthetic blend. With all the controversy regarding synthetic use in the rotary engine, I decided against using the Amsoil. I believe the Motorcraft oil will be OK. It is a highly rated oil on those forums.

 

Geez All this and the fundamental question of which viscosity 5W/20 or 5W/30 seems to go unanswered? 4-Get Synth or Reg Oil what is the right viscity range and it seems 4-Get the Owners Manual 5W/20 - what is best - period?