Oil Analysis Worth It?

[9krpmrx8]

I have read both good and bad and I have searched a bit but this forum software has me a bit confused for now.

Anyway, I have a Mazda RX8 with a new engine. This car is daily driven 15-20 miles day 70% highway 30% traffic and sees about five track days a year and a few hard cruises through the hills. The engine was broken in to 1500 miles on Mazda 5W-20 and then changed to GC 0W-30 for 1800 miles. I then took a sample and sent it to Blackstone and I am awaiting the results. How much should I trust these Analysis' overall? Should I use different test facilities each time? If so which facilities?

A little history:

This RX8 has 99,000 miles on it and is on its third motor. Keep in mind I live in San Antonio, Texas. The first motor went at 22k running Mobil 1 5W-20 with regular 3,000 mile OCI's. There was a recall and they flashed the computer because the OMP(oil injection system) was not injecting enough oil to lubricate the internal seals in the combustion chamber.

My second motor (on updated flash) ran Castrol GTX 10W-30 (belief was that 5W-20 was too thin for 100+ degree weather) and it lasted 72,000 miles before it lost compression. So obviously the computer flash helped a bit but it still failed early.

My third motor (glad Mazda extended the warranty) now has about 3000 total on it and I am using premix (oil/lubricant) in every tank of gas. In addition I recently purchased and adapter that improves the factory oil injection system by instead of pulling dirty engine oil to inject into the combustion chamber it will pull clean premix oil from a reservoir to inject instead. I would like to get 100k out of this motor.

 

[Bill in Utah]

Thought that rotary motors were NOT to use syn oil?

3 motors in less than 100k?

Wow..

What does Mazda tell you to use for the engine?

Call up blackstone and ask them if a UOA works well for Rotary motors? Also I would not run a UOA until you get some more miles.

 

[crazycrak]

maybe thats why it only lasted 20K

 

[9krpmrx8]

Well Mazda has said not to use synthetic in the rotary (which is why on the second motor I did not) but now they offer it in Japan (all engines come from the same plant) from the dealer so we are all a little confused.

They recommend 5W-20 (which has to be partially synthetic right?) but they don't recommend that low of a viscosity in other countries on the same motor so many believe the recommendation is to meet CAFE standards for mileage and not the best for the engine in terms of longevity.

After doing my own research i have found that instead of going by the numbers on the bottle is not how your should research but rather by the spec of the oil. So, that is how I settled on GC 0W-30. I would run 0W-40 but I cannot find it locally. I think cold start up is an issue as well as seal lubrication so I am attacking the issue from different angles.

All input is welcome.

 

[9krpmrx8]

Some guys don't agree on the oil specs mindset and swear by using heavier 20W diesel oils. I used Castrol GTX 10W-30 for 72k on time oil changes at 3k and I lost compression.

Put simply, I have just read about the bottle numbers being misleading and lower numbered oils performing as good or better than higher labeled oils.

 

[Bill in Utah]

Originally Posted By: 9krpmrx8
Well Mazda has said not to use synthetic in the rotary (which is why on the second motor I did not) but now they offer it in Japan (all engines come from the same plant) from the dealer so we are all a little confused.

They recommend 5W-20 (which has to be partially synthetic right?) but they don't recommend that low of a viscosity in other countries on the same motor so many believe the recommendation is to meet CAFE standards for mileage and not the best for the engine in terms of longevity.

After doing my own research i have found that instead of going by the numbers on the bottle is not how your should research but rather by the spec of the oil. So, that is how I settled on GC 0W-30. I would run 0W-40 but I cannot find it locally. I think cold start up is an issue as well as seal lubrication so I am attacking the issue from different angles.

All input is welcome.


Everything I've read on rotary engines says NO syn.

Every time I've seen someone use syn they end up like you did.

I don't know if the oil you shown has some additive that helps a rotary but unless you use that brand I'd be using what works.

Check out a Mazda rotary forum and see what other members are using. Watch out for the closet salesperson trying to sell stuff. (Plenty of those "members" on every site)

Personally if I lived in Texas I'd prob run a good conventional oil in a 5w-30 or 10w-30 and call it a day. Watch your OCIs and get on with it.

Take care, Bill

 

[Smokescreen]

Up here in Canada, my friend runs nothing less than regular conventional 15w40 and changes it every 2000miles, in his second generation Rx-7 turbo with some pre-mix additive as well. He has over 100,000 miles on his easily, and he has only replaced the apex seals once, when he first got it. This guy drives the thing like its on a track. Even though the engine isn't as modern as yours, I think he and all his friends are onto something as far as longevity goes. Some of his friends are doing crazy things with these engines, with various mods like: 3 rotors, huge turbos, 6 puck clutches, dog gears on various cars, these guys can tear down a rotary engine with thier eyes closed so they know their stuff. They all keep the oil thick and change it often.

 

[9krpmrx8]

Thanks for the responses guys. Yeah I ran conventional 10W30 with clock work 3,000 mile oil changes and the motor still failed (albeit lasted 50k more than the original engine).

The real reason for the failures I believe is a combination things.

1. Poor oil injection system (last gen RX-7 had three oil injectors and the latest gen RX8 has three but 2st gen RX8 has only two)

2. Poor 5W20 doesn't cut it in Texas heat.

3. Oil injected into combustion chamber is used engine oil not designed to burn efficiently so carbon build up is an issue.

4. Oil temps are too high even with two oil coolers.

 

[FZ1]

Will Mazda spring for another motor for you? Let the dealer do all the oil changes on that Thang,Tex.

 

[9krpmrx8]

Yeah Mazda has paid for two motors but the warranty is up at 100k so they won't pay for another (new engine was replaced at 96,000). The car is paid for but I would like to keep it for another 100k if I can.