RL 5w30 vs Mobil 1 0w40

[robertcope]

I'm sure this question has been asked in different forms before, and I've searched an searched, but I figure I'll ask it again as a lot of the answers were from five or six years ago.

I have a '99 Miata that puts on most of its miles around race tracks. Motor is stock with your usual bolt-ons. I've been running Mobil 1 0w40 without any issues and have no problem continuing to do so, but I'm thinking of trying Red Line 5w30. I like the idea of running a slightly thinner oil with the same HTHS.

Thoughts, experiences?

robert

 

[aquariuscsm]

I`d stick with the M1. You`re probably like me,and love to try new/different oils and such. It really can be alot of fun and very interesting. Out of all the experimenting I`ve always gone back to M1. Best "bang for your buck" synthetic imo. It`s cheap,can be bought anywhere,and is a proven performer.

 

[buster]

I agree with what aqua said, but RL is a fine choice for those types of conditions you are describing. M1 as well. Both are good but very different formulations.

 

[Torrid]

I tend to go with what is more cost effective but still gets the job done. They would be Mobil 1.

 

[hemitom]

Mobil 1, is more cost effective, For your application, you well only ever know for sure until you try it yourself. I'm sure no harm would be done by running two trial oci's. One as a base line and remove previous oil, and other to collect true data.

 

[dparm]

Both of those oils are quite thick (HTHS of 3.8). Are you sure you need something like that?

 

[robertcope]

Originally Posted By: dparm
Both of those oils are quite thick (HTHS of 3.8). Are you sure you need something like that?


Need? Hard to say, but I believe that for my use, it makes a lot of sense if optimizing for engine life. That's one of the reasons Red Line 5w30 appeals to me, it is a thinner oil but maintains the HTHS. I could be confused...

robert

 

[dparm]

You want as thin as possible but as thick as necessary. What's the car spec'd for?

 

[robertcope]

Originally Posted By: dparm
You want as thin as possible but as thick as necessary. What's the car spec'd for?


That is a very broad statement that is probably a reasonable rule of thumb on some level, but really not meaningful without more specific definitions. The recommended oil for these cars is also very broadly scoped. This is from the Australian owner's manual:

robert

 

[robertcope]

I had never actually looked in the factory workshop manual. It is pretty sparse on detail, simply saying 10w30 when above -13F and 5w30 when below 32F and API SG, SH, or SJ. It says also says oil pressure should be between 43-56psi at 3K rpm when at operating temperature, but that it may vary with oil viscosity.

robert

 

[CATERHAM]

Originally Posted By: dparm
You want as thin as possible but as thick as necessary. What's the car spec'd for?


Correct, and the only way to answer than question precisely is with an oil pressure guage. But generally speaking, if your not seeing very high oil temp's then a high VI 0w30 or 5w30 is probabily more suitable.

Regarding Red Line 5w30 vs Mobil 1 0W-40. Because of Red Line's unique POE chemistry you must look past the low kinematic viscosity values. Red Line is actually heavier than Mobil 1 at all temp's for two reasons: It's has a much lower VI of 162 vs 185 for Mobil 1 and since it contains no VII's it will not shear.

 

[dparm]

I would stick with Mobil 1 0w40, though I still think that's a bit thick for your motor. Won't really hurt things, but it is sapping some power.

 

[bluestream]

Originally Posted By: robertcope
That is a very broad statement that is probably a reasonable rule of thumb on some level, but really not meaningful without more specific definitions. The recommended oil for these cars is also very broadly scoped. This is from the Australian owner's manual:

robert


You said the car spends most of its time on the race track, so you can throw the owner's manual out.

Go by your oil temps and pressures..

 

[Ibrahim]

if you track a lot, I think you should consider Red Line 5w30 & Red LineI 5W-40 & ... also heard from few friends that have used AMSOIL Signature Series 10w30 successfully!

another two oils you can get it for cheap and are excellent for tracking are Shell Rotella T 5W-40 & Mobil 1 Turbo Diesel Truck 5W-40...

You will not see much change in gas combustion if you switch to any of these above mentioned oils from Mobil 1 0W-40

 

[dparm]

We should probably clarify...is this a track-only car, or does it see regular street driving too?

 

[robertcope]

Originally Posted By: dparm
We should probably clarify...is this a track-only car, or does it see regular street driving too?


It is street legal, but a very high percentage (say, 90%) of its driving is on the track.

robert

 

[A_Harman]

For a naturally aspirated engine, I think Red Line 5w30 is overkill on HTHS. Something like Red Line 0w30 (3.2 HTHS) or 5w20 (3.3 HTHS) would give your engine all the protection it needs. But I shouldn't be one to talk; I'm running a blend of Red Line 5w30 and 10w40 in my Camaro. (It's a long story.)

 

[robertcope]

Originally Posted By: A_Harman
Something like Red Line 0w30 (3.2 HTHS) or 5w20 (3.3 HTHS) would give your engine all the protection it needs.


I was actually looking at Red Line 5w20 this morning. I know some Spec Miata teams run it. Seems like it would be a reasonable choice for someone looking for power.

robert

 

[CATERHAM]

Red Line 0w30 may be their "best" street oil because it's not "too" heavy; it is a true 30wt oil, but most importantly it has a high modern VI of 183. This high VI is achieved without much in the way of VII's and therefore has proven to be very shear resistant.

On the other hand Red Line 5W-20 (it's an old formulation) is one of Red Line's least attractive oil's due to it's uncompetitively low 145 VI; something most over look. Just try and find a multi-grade oil with a lower VI; you won't be able to. I've used this oil in the past and it's about as thick as Mobil 1 0W-40 at room temperature (based on actual engine oil pressure) and progressively thicker at colder temp's.

When Red Line developed their 0w30 it pretty much rendered their 5W-20 oil obsolete.

But you haven't commented on whether you have an oil pressure guage installed in your Miata track car, something you should have? While it goes on a lot on this forum, choosing an oil viscosity without reference to OP in a track car is a bit silly.