Which Royal Purple?

[Finite35]

Heya Fellas!

Based on the many favorable reviews, I'm giving my baby Royal Purple to drink. My question is, which grade do you guys use? 5W-30? 40? What's your recommendation?

Thanks!

[joe603]

For Canada, I'd use 5W-30.

[Tampa G35 Sedan 6MT]

i use 5-30 also..

if they make a 5-40 use that because it has a higher heat content!

But I don't think they make a 5-40!

DJ

[Finite35]

Alright, thanks for the help....as always

[tollboothwilley]

5w-30 in the winter for me (Utah)

10w-30 in the summber for me (AZ)

[silver37]

If yours is an '09, the RF might not have the correct protection. The RP sold at my local Pep Boys is the last generation of protection (I forget which one ...SG?), so it's off by one generation from what's recommended in the manual and could void your warranty if something goes wrong.

[Finite35]

Well I got 5W-40 but now I'm thinking whether or not I should've got 5W-30. The Infiniti guys will throw it in for me on Monday so I have a couple of days to think about it.

[pfarmer]

Well I got 5W-40 but now I'm thinking whether or not I should've got 5W-30. The Infiniti guys will throw it in for me on Monday so I have a couple of days to think about it.

If one has an 09 I would go with the Infiniti oil while under warranty (not your case by the looks of it). I would also go with 5-30 regardless of the oil type for a newer car (lower mileage) as 5-40 may actually increase your cooling needs as well as not providing proper lubrication.

Perry

[Finite35]

Thanks pfarmer. My car is still under warranty. I'll exchange the oil I bought for 5-30. Thanks for all the help!

[silver37]

The rule with oil is you can always safely go lower on the low end - it will only give you better lubrication at low temps, but going higher on the high end will actually make you lose mileage since your engine was made (closer tolerances, etc.) to perform best with no higher (thicker) than 30W, so going with 40W will bog it down. I think Car and Driver or Road and Track covered this in one of their issues.

[Finite35]

Thanks Silver,I got my oil change done today, but prior to that I exchanged it for 5W-30:)Thanks for the helpful advice!

[pfarmer]

Thanks Silver,I got my oil change done today, but prior to that I exchanged it for 5W-30:)Thanks for the helpful advice!

Good. If you go with oil of a higher viscosity than needed you may well end up with several issues. Like silver was stating it takes more effort to push the oil through the system. Your oil may also not properly flow to all of the areas it needs to flow to. Pushing your oil through your system also generates heat that has to be removed someplace, such as your cooling system. If the rate of flow decreases then it stays in one place longer (retention time) which allows it to get hotter before it moves onward through the system. If it is hotter earlier in the cycle then it has less heat absorbing capability in the latter parts of the cycle, the difference between the temperature of the cooling medium and what it is cooling.

Think about this in the terms of a boiler. If water in a boiler is not pushed through the system fast enough it turns to steam. Since the water in a boiler is the cooling medium for the boiler tubes the tubes will form hot spots and eventually will fail. The exhaust gas temperature will raise since the temperature is not being absorbed by the cooling medium which may overheat the rest of the gas cycle.

Basically the same concept in a car, just different thermo dynamics.

From what I have studied on the topic of the low numbers is that typically there is little benefit (if any) between a higher viscosity oil such as 10-30 over a lower viscosity oil such as 5-30 at the higher temperatures. At low temperatures the 5 provides better lubrication until the engine reaches operating temperatures (translates into easier starting as one benefit).

Perry