Ideal oil for built 13b (rotary)

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Apr 26, 2022
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Hey guys have a question regarding the ideal oil for my built 13b.

Long story short i have a rebuilt 13b with a single turbo aiming for around 400whp. The tuner recommends i run a 15w-50 for good oil pressure and he was recommending motul 300v. Being that im in New Zealand, Penrite sells a similar product in their 10 Tenths range which is also a 100% pao esther blend and is about 40% cheaper so this is what i plan to run.

My main concern with this oil is that it has a flash point of 206 degrees compared to motuls 236 degrees and its antiwear package is around 1800ppm zddp.
Ideally i want an oil with low deposits and historically this has meant Mazda will only endorse full mineral oils, but with a build of this nature i feel like a full synthetic will offer better and more consistent protection.
My concern relates to whether the Penrite's relatively low flashpoint and high zddp content is likely to be an issue for deposit build up.
Also for what its worth i plan to premix and will be running mobils 2t full synthetic 2stroke.
Any insight or clarification on this matter would be greatly appreciated, thank you.
 
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That Penrite oil doesn't sound so bad but your concerns are valid for that type of engine. Also what kind of emissions laws do you have in new Zealand. Is it important for the zddp to not burn and damage the catalytic converter to pass inspection? A 1993 is pretty old but I don't know how NZ laws work.
 

Aramir

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That Penrite oil doesn't sound so bad but your concerns are valid for that type of engine. Also what kind of emissions laws do you have in new Zealand. Is it important for the zddp to not burn and damage the catalytic converter to pass inspection? A 1993 is pretty old but I don't know how NZ laws work.
Cat health is not an issue
 
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SR5

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Hi OP,
I'm not too sure where you are finding your Penrite flash point as I can't find it easily on their web page. I did find Motul and for FP they are using test ASTM D92. Just make sure both are measuring to the same standard, otherwise it's not a fair comparison.

I don't know much about Motul products, but I do use and like Penrite products, I have a lot of respect for their 10-Tenths oils which are 100% PAO & Ester. They are mostly PAO for the record. Nulon Racing use PAO & AN. Again, I don't know much about Motul, I always assume more ester from their early advertising, but this was years ago and I never look into it, as it was out of my price bracket.

Anyway, all are great products, and I personally would use none in a Rotary engine. To me rotary engines burn a little engine oil by design and you want it to burn clean. Here I believe conventional mineral oils with their lower flash points, burn cleaner. You are sort of caught between a rock and a hard place, as turbo implies synthetic but rotary implies mineral. So it's your call here.

Me? I would run Penrite 20W-50 mineral, and change it regularly. I would also get a turbo timer, to allow the engine idle a bit after a hard run, to cool down with some oil still flowing through the turbo. It's the sitting oil that gets cooked by the hot turbo.

 
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SR5

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From Penrite:

Premium Mineral 20W-50 is designed for use in modern 4, 6 & 8+ cylinder naturally aspirated, supercharged & turbocharged engines. It is also suitable for use in rotary engined vehicles such as Mazda RX series vehicles that require this viscosity grade.

Typical Data

Density at 15°C, kg/L0.880
Viscosity, Kinematic, cSt at 40°C163
Viscosity, Kinematic, cSt at 100°C18.0
Viscosity Index122
Cold Cranking Viscosity, cP at -15°C7311
Zinc, Mass %0.108
Sulphated Ash, Mass %0.83
Total Base Number (TBN)7.6
 

Aramir

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Joined
Apr 26, 2022
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Hi OP,
I'm not too sure where you are finding your Penrite flash point as I can't find it easily on their web page. I did find Motul and for FP they are using test ASTM D92. Just make sure both are measuring to the same standard, otherwise it's not a fair comparison.

I don't know much about Motul products, but I do use and like Penrite products, I have a lot of respect for their 10-Tenths oils which are 100% PAO & Ester. They are mostly PAO for the record. Nulon Racing use PAO & AN. Again, I don't know much about Motul, I always assume more ester from their early advertising, but this was years ago and I never look into it, as it was out of my price bracket.

Anyway, all are great products, and I personally would use none in a Rotary engine. To me rotary engines burn a little engine oil by design and you want it to burn clean. Here I believe conventional mineral oils with their lower flash points, burn cleaner. You are sort of caught between a rock and a hard place, as turbo implies synthetic but rotary implies mineral. So it's your call here.

Me? I would run Penrite 20W-50 mineral, and change it regularly. I would also get a turbo timer, to allow the engine idle a bit after a hard run, to cool down with some oil still flowing through the turbo. It's the sitting oil that gets cooked by the hot turbo.

I had to phone their head office to get it, not sure why they don’t list it
 
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Aramir

Thread starter
Joined
Apr 26, 2022
Messages
10
Hi OP,
I'm not too sure where you are finding your Penrite flash point as I can't find it easily on their web page. I did find Motul and for FP they are using test ASTM D92. Just make sure both are measuring to the same standard, otherwise it's not a fair comparison.

I don't know much about Motul products, but I do use and like Penrite products, I have a lot of respect for their 10-Tenths oils which are 100% PAO & Ester. They are mostly PAO for the record. Nulon Racing use PAO & AN. Again, I don't know much about Motul, I always assume more ester from their early advertising, but this was years ago and I never look into it, as it was out of my price bracket.

Anyway, all are great products, and I personally would use none in a Rotary engine. To me rotary engines burn a little engine oil by design and you want it to burn clean. Here I believe conventional mineral oils with their lower flash points, burn cleaner. You are sort of caught between a rock and a hard place, as turbo implies synthetic but rotary implies mineral. So it's your call here.

Me? I would run Penrite 20W-50 mineral, and change it regularly. I would also get a turbo timer, to allow the engine idle a bit after a hard run, to cool down with some oil still flowing through the turbo. It's the sitting oil that gets cooked by the hot turbo.

Comparing the the flash points of 10 Tenths vs another recommended oil - Castrol GTX 20w-50 mineral: Penrite FP - 206, Castrol FP 201.
So they seem similar, unsure if theres anything inherent in either PAO or mineral that would result in cleaner burning or less deposits.
 

SR5

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Comparing the the flash points of 10 Tenths vs another recommended oil - Castrol GTX 20w-50 mineral: Penrite FP - 206, Castrol FP 201.
So they seem similar, unsure if theres anything inherent in either PAO or mineral that would result in cleaner burning or less deposits.
Yeah, but there are two FP tests, open cup and closed cup, you need to compare like with like.

Anyway, I was more saying mineral oil is supposed to burn cleaner in an engine. The FP is more of a side issue to me, not a direct cause and effect.

BTW @Motu is a NZ mechanic with a lot of experience, and he may be along to help soon.

Anyway, good luck, no wrong choice here, whatever you feel most comfortable with.
 
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I never had good luck running synthetics in my rotary's.They always gave me sticky seals. I had the best luck with valvoline 20/50 in the white bottle. and amsoil dominator as my premix. 240:1
 

Aramir

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I never had good luck running synthetics in my rotary's.They always gave me sticky seals. I had the best luck with valvoline 20/50 in the white bottle. and amsoil dominator as my premix. 240:1
Appreciate the anecdote, what oil were you running when the seal stuck?
 
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