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Ok guys, what's the best oil and oil filter to put in the 2006 Mazdaspeed 6 (123k engine)? I just bought the Rotella 5w40...any inputs?
 

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It's really as simple as the correct OEM filter and any quality full synthetic. The same weight as the manual calls for.

You're going to get several different opinions. Why would you use something other than what the manufacturer tells you to use?

IMO the engineers that built your car know more than any Joe Blow on this forum.

Best of luck with your new engine. May it serve you well.
 

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Use the manufacturer-specified weight, gasoline-rated (carries a "S" rating) oil, and were it my engine I'd choose a fully-synthetic formulation as they are far more-capable of handling heat and, all other things being equal, have far less VIs in them (which can and do shear down over time) to obtain multi-weight ratings than a dino-based oil. I like Pennzoil Pure Platinum, which is available in the recommended weight; in 0w20 in my SkyActive (Gen 3) car it has provided excellent service.

I don't much care for Pennzoil's dino-based oils and never have, but their synthetics are, like most other manufacturers, excellent.
 
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No more oil threads please.

If you do some research, lots and lots of Mazdspeed owners, amongst others such as Subaru WRX/STI owners use shell rotella with their cars. They claim it helped with oil consumption compared to Mobil 1 (which is poo, IMO)

Pennzoil is good quality oil.
 

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As long as you use the appropriate types of oil and filter changing it regularly matters more than what kind you're using. This engine is prone to fuel dilution, so it's recommended to change it pretty frequently with synthetic. Also, don't worry that the oil turns black pretty quickly, that's fairly normal and doesn't mean that the oil already needs to be changed.

Personally I use Pennzoil Platinum 5w-30 in mine especially in the winter. It's consistently rated as a top oil and it's pretty cheap on Amazon or at Walmart. I've used Rotella T6 5w-40 as well and it seemed fine although my car seems to rev a little better with the thinner oil. Others swear by using the thicker oil.

On filters, just use anything good, which mostly means don't use the cheap Frams. The Mazda OEM filters are cheap. I've got a Mobile 1 in mine right now which is a bit overpriced but I was in a hurry and that's what Advance Auto had in stock.
 

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Ok, for non DISI engines stick with manufacturers specs. Now for DIS engines. MS6 have experienced fuel dilution of oil. Essentially, put in a 5W30 and a month or two later, the oil will dilute to a lighter weight. This would effect the oil seepage in the K04 turbo bearing and thus smoking in the tailpipe. Thus almost all MS6 owners went to 5W40 to prevent that. We have stuck with 5W40 even when changing turbos.

I use Rotella 5W40 for the life of the MS6. Seen smoking tailpipe using a qt of 5W20 when I was short of 5W30. I recommend you researched this oil topic. Highly advisable to use 5W40 synthetic.
 
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Ok, for non DISI engines stick with manufacturers specs. Now for DIS engines. MS6 have experienced fuel dilution of oil. Essentially, put in a 5W30 and a month or two later, the oil will dilute to a lighter weight. This would effect the oil seepage in the K04 turbo bearing and thus smoking in the tailpipe. Thus almost all MS6 owners went to 5W40 to prevent that. We have stuck with 5W40 even when changing turbos.

I use Rotella 5W40 for the life of the MS6. Seen smoking tailpipe using a qt of 5W20 when I was short of 5W30. I recommend you researched this oil topic. Highly advisable to use 5W40 synthetic.
Realistically speaking, this engine probably deals with fuel dilution because it is an older design DI system. Alot of it also boils down to the quality of the piston rings which the engineers decided to use, although how the engine was broken in/treated must be considered as well because worn piston rings in an abused motor will cause fuel dilution.

Fuel dilution is absolutely a thing even with older engines which still have port injection. Again, alot of it boils down to the quality of the piston rings. Occasionally mixing some fuel system cleaner in with your fuel would probably be helpful.

Like we have discussed before in the past, it's the additives inside the engine oil which are combating the fuel dilution and preventing the oil from thinning down a grade, not the actual thickess of the oil itself. Thicker oil will definetely help provide more cushioning between critical moving parts within the crankcase and provide a better piston ring seal which limits fuel dilution and oil consumption, but it's the additives which really count. Shell Rotella with it's diesel based additives is pretty excellent at fighting with this, but not all synthetic oils are created equal. For example, 5W40 Mobil 1 is definetely going to burn faster than even some good quality 5w30 oils.

For me personally, with this car I would use Motul or Redline 10W50 oil in the summer and 5W50 (or 5W40) in the winter. These oils are pricey but very well worth it judging by how excellent they are at dealing with even the worst forms of fuel dilution.
 

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Best engine oil I’ve ever seen against fuel dilution is Renewable Lube’s BioSyn. Their 5W40 showed markedly better wear performance and fuel dilution management in a group of Audi A8s. I had them make me a straight SAE20 for my fleet back around that time, too, to get wear and fuel dilute under control. That product is now available through Amazon, so easy peasy to get.
 
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Best engine oil I’ve ever seen against fuel dilution is Renewable Lube’s BioSyn. Their 5W40 showed markedly better wear performance and fuel dilution management in a group of Audi A8s. I had them make me a straight SAE20 for my fleet back around that time, too, to get wear and fuel dilute under control. That product is now available through Amazon, so easy peasy to get.
Looks really good. Doesnt ship to canada though... darn.
 
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Ok, for non DISI engines stick with manufacturers specs. Now for DIS engines. MS6 have experienced fuel dilution of oil. Essentially, put in a 5W30 and a month or two later, the oil will dilute to a lighter weight. This would effect the oil seepage in the K04 turbo bearing and thus smoking in the tailpipe. Thus almost all MS6 owners went to 5W40 to prevent that. We have stuck with 5W40 even when changing turbos.

I use Rotella 5W40 for the life of the MS6. Seen smoking tailpipe using a qt of 5W20 when I was short of 5W30. I recommend you researched this oil topic. Highly advisable to use 5W40 synthetic.
Also, I must mention; that short distance driving will dilute the oil supply to ANY engine period. a good 30 minute drive, preferably highway each week is the absolute minimum.
 

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Discussion Starter #13
Funny you guys recommended the Rotella 5W40 because that's what the previous owner used and what my mechanic recommended too. I bought some last night. Thanks again guys!
 
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