ROUSH 427IR Oil recommendations.


My Superformance MkII is currently undergoing it's engine install, it is having a Roush 427IR with Borla 8 stack fuel injection - because of the Borla the engine has been supplied without initial test bed running.

Information from Roush on oil recommendation appears limited to "10w30. Synthetic after 3000 miles".

I plan to do initial running with Millers Competition Running in Oil 10w40 (Mineral), with an initial oil and filter change at 50 miles, and will be sure to run in quite hard to bed in the piston rings (e.g. Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power) - then what? More mineral or go semi-synthetic until 3000 miles?

I would like to get the car out on track once it's run in, though it will be mainly road use - would 10w40 (synthetic) be better than 10w30 - I know many advocate 20w50 but I wonder if this might be a little thick for road use. I will be using an Accusump for pre-oiling.

I've done several google searches but come up with more questions than answers. Any specific manufacturer recommendations? What about ZDDP levels etc?

Thanks for any advice


Randy V

Staff member
Lifetime Supporter
In my opinion ---
If your engine is equipped with a roller cam, then the only thing that is breaking in is the piston rings and that happens pretty quickly (within 50 miles) as long as you load the engine up periodically with full throttle / low RPM acceleration. This will increase the cylinder pressures and force the rings to seat properly.
Skip the mineral oil and use a good break in oil such as Joe Gibbs.
I run Rotella T6 5w40 synthetic once the rings are seated and never look back.
The only reason to run a higher zinc than available in the T6 is if you are running a flat tappet cam.
Thanks very much - so Randy you would advocate going fully synthetic after 50 miles or so, assuming the piston rings have been properly seated? It has a roller cam.

I am presuming the Millers CRO is similar to Joe Gibbs, intended uses certainly seem the same Millers Oils CRO 10w-40 Engine Oil

Any other views? I had thought I would do a 2nd stint on the Millers between say 50 to 400 miles, but given that Millers and Joe Gibbs suggest no more than 500 miles per change, that would be a lot of changes to get to 3000 miles before going fully synthetic, as suggested by Roush.

After full run in, does 10w40 seem a reasonable compromise for road/track use? - we don't get the really cold winters, or really hot summers that some of you guys get stateside! Winter cold starts will be very few and far between, and as I mentioned I will be pre-oiling with an accusump.

After full run in 10-40 synthetic is a good choice for your use. I do track days a few times a year with my Roush 427SR and use that weight unless weather is really hot. For track days over 90F I change to 20-50.

Randy V

Staff member
Lifetime Supporter
As Jac points out, yes the distributor drive gear is also wearing in - but should be friendly with the camshaft by the time the rings are seated as well. I advocate dumping that first load of oil & filter pretty soon after the rings are seated as that will also flush the assembly lube from the system.. After that, I just go straight away to the synthetics. 10w40 should be just fine for you as long as you allow the engine to warm up before jazzing the throttle too hard.
Valoline Vr1 conventional Race oil has a higher film strength, Its 103.505 psi.Best bang for our buck. Amsoil is 95k,royal purple,exterm race is 74k. Rotella is 74k Royal purple street is 64k. Tests results are printed in Pantera owners club newsletter may 2013. Some JPL type guy that had excess to test lab decided to see what the difference was between oils. He also gave a zink, phos. and moly content. For me the film strength is what it's all about at the end of the day!
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Randy V

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Odd numbers Randy.....
i mean 64k, 74k, 95k and then 103.505 PSI. Or was that supposed to be a comma - 103,505 PSI..
We appreciate the info and I don't disagree at all about film strength.
Would really like to see Zinc numbers if your friend has them...
Randy The VR1 is over 100,000 psi sorry about the comma. I'l get the zinc, it was all over the board. And Zinc is the one we all talk about but there is a huge difference between 64,ooo psi and 103.000 psi.

Howard Jones

So here is what I used to break in my last motor. I added it to the fill amount of straight 30weight oil (8 quarts) and did the standard first start run in. That was about 30 min of run time including a rough carb adjustment and timing setting.

Then a drained the lot and replaced it with another bottle of the same stuff and a refill of 30 weight normal motor oil. I run it for one year (about 2000 miles or so I would guess) and throw it away every winter. Same refill blend each time.

New clean oil and a quality filter (I use K&N) along with proper control of oil temp is far more important than expensive synthetic oil that lasts longer. IMHO

COMP Cams Engine Break-In Oil Additive 159 - Free Shipping on Orders Over $99 at Summit Racing

This is the other ZDDP stuff that one of my drag race friends recommended a few years ago.

Best Oil Additive & Cam Assembly Lube from ZDDPlus
Test Conditions. All oils were tested at 230 F. Multiple tests were performed to ensure repeatabitity and accuracy.

1. 10W30 Lucas Racing Only synthetic = 106,505 psi
zinc = 2642 ppm phos = 3489 ppm moly = 1764 ppm
Note: Not suitable for street use.
2.10w30 Valvoline NSL conventional Racing oil = 103,846 psi
zinc = 1669 ppm phos = 1518 ppm moly = 784 ppm
Not for street
3. 10w30 valvoline VR1 conventional race oil ( silver top) = 103,505 psi
zinc = 1472 ppm phos = 1544 ppm moly = 3 ppm
4. 10w30 VR1 Synthetic racing oil, API SL ( black bottle) = 101.139 psi
zinc = 1180 ppm phos - 1112 ppm moly = 162 ppm
5. 30 wt Red Line Race Oil synthetic = 96, 470 psi
zinc= 2207 ppm phos =1112 ppm moly = 162 ppm
6. 10w 30 Amsoil Z-Red oil synthetic = 95,470 psi
zinc = 1431 ppm phos = 1441 moly = 52 ppm
7. 5w30 Maxima RS530 synthetic racing oil = 91,162 psi
zinc = 2162 ppm phos = =2294 ppm moly = 181 ppm
8. 10w30 Quacker State Delfy API SL semi-synthetic = 90,226 psi
zinc = 1221 ppm phos = 955 ppm moly = 99 ppm
9. Joe Gibbs HR4 Hotrod Oil = 86,270 psi
zinc = 1247 ppm phos = 1137 ppm moly =24 ppm
10, 15w40 Redline Diesel oil synthetic = 85,663 psi
zinc = 1615 ppm phos = 1551 ppm moly = 173 ppm
11. 5w30 Lat synthetic racing oil, API SM = 81,800 psi
zinc= 1784 ppm phos = 1539 ppm moly = 598 ppm
12. 5w30 Lucas synthetic = 76,585 psi
zinc =1134 ppm phos = 666 ppm moly 0
13. 5w50 Catrol edge sytec = 75,409 psi
zinc = 1252 ppm phos = 1197 ppm moly = 71 ppm
Below is modest protection group
14. 5w30 Royal Purple XPR = 74,860 psi
zinc = 1421 ppm phos = 1338 ppm moly = 204 ppm
15. 5w40 Mobil 1 turbo diesel truck synthetic = 74,312 psi
zinc = 1211 ppm phos = 1168 ppm moly = 2 ppm
16. 15w40 Chevron Delo 400LE deisel oil conventional = 73,520 psi
zinc = 1519 ppm phos = 1139 ppm moly = 80 ppm
17. 15w40 Mobil Delvac 1300 super Diesel oil conventional = 73,300 psi
zinc = 1297 ppm phos = 1944 ppm moly = 46 ppm
18. 15w40 Farm rated heavy duty performance diesel oil convertional = 73,176 psi
zinc = 1325 ppm phos 1234 ppm moly = 2 ppm
19. Shell Rotella diesel oil conventional 72, 022 psi
zinc = 1545 ppm phos = 1062 ppm moly 0
20. ow30 Brad Penn,Pen grade 1 semi synthetic = 71,377 psi
zinc = 1621 ppm phos = 1437 ppm moly 0
21. 15w40 "old shell Rotella T diesel oil conventional = 71,214 psi
zinc = 1171 ppm phos = 1186 ppm moly=0

There are lots more . Do not want to type all of them. Worst protection are break-in oils.
34.10w 30 Comp Cams Break in oil conventional = 51,749 psi
zinc 3004 ppm phos 2613 ppm moly = 180 ppm
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Randy V

Staff member
Lifetime Supporter
Wow - great info Randy!!!! Thank you for taking the time to enter all this and share with us!
My car has a Roush 347 and am getting mixed opinions about what oil to use. Previously I would be using a fully synthetic oil however Roush are recommending 10w-30 mineral oil. My knowledge of oil is limited but I understand synthetic is superior to mineral in almost every way. When I ask Roush why they recommend mineral they just say they have had good experience with mineral but will not respond when asked why it is superior to synthetic. So why are they recommending it? Is there something special about their engines that need mineral oils?

Surely a highly quality ester based synthetic is going to provide superior protection especially in a car with a wet sump that can generate high lateral g. Any temporary loss of oil pressure will surely be less damaging if the oil has higher film strength?

Happy to go with 10w-30 but why mineral?????!!!!
If you run a full synthetic oil for run in with a roller cam you may find its actually too slippery and allow the roller to skid on the lobe- this info was passed on to me many years ago from the guy who owned Kelford Kamtech here in NZ at time who was working closely with CC. I can understand Roush not wishing to discuss the topic, its one of those bench racer subjects that wont go away.

Howard Jones


Synthetic Oil vs. Mineral Engine Oil - Changing from Mineral to Synthetic Oil

Synthetics have an advantage IF you run the oil hot, like without a cooler in 105 degree weather in stop and go traffic for 2 or 3 hours in your 5 quart 4 banger that runs normal water temps at 215F. Many modern cars do exactly that.

If you do have a oil cooler and manage oil temp to normal oil (190F -220F) temps then I don't think that you need to use expensive synthetics. Keeping water temp low (180F- 200F) will really help the oil heat control also. That's my 2c.
My situation is not break-in. Looks like semi-synthetic then. Keep to the happy middle ground.

Oil temp is intresting though. Temp sensor is in the pan which is much cooler than what comes out of the engine and goes through the cooler. I wonder what it is coming out of the engine. Also the Mocal sandwich plate oil cooler thermostat does not seem to restrict flow to the cooler. Cooler starts warming as soon as the engine does. That should be a separate thread.

Howard Jones

The oil temp that I think is the most important is the temp of the oil being delivered to the bearings not the temp as it leaves the bearings. So that would be the oil that is leaving the oil pump and being pumped down all the oil galleys. The oil in the pan in a system that does not have a oil cooler is generally the way it is done. You can see that the oil temp is pretty much the same through out this kind of system and it is difficult to sample oil temp in the drain back loop (hotter oil).

With a cooler:

The oil is pumped from the pan, to the outside of the sandwich plate, through the filter, out of the sandwich plate center port, to the oil cooler and back to the sandwich plate return port and on to the oil galleys in the motor. So if you what to sample oil temp before it goes to the bearings it would be after the oil cooler but before it is returned to the motor bearings.

This is how I have done my cars, I don't say this is the only right way, just the way I have done it.
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One of the better info videos I've found

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