What Grade Oil For A High Powered Barra?

[Jman]

Hi guys.

I'm getting a major service done tomorrow and was hoping to get a little info about engine oils.

I've spoken to a few mates with built import motors and the general trend seems to be running a thinner oil on higher HP applications.

Ever since day one I've used Nulon 10w40 in my ute, recently I've tried a Motul Turbolite of the same grade, however I found oil temps to sit a bit higher than the Nulon. Thus why I'm going to stop using it.

My motor isn't built its still a bf1 xr6t motor with the piss ant rods. Never had a problem with the motor always been kept upto date with 7,500 services when stock and 5,000k services once tuned. It has however travelled a fair few k's for its age; It's just ticked over 103,000ks. The oil pressures/temperatures have always stayed the same over the life of the car. When the car is hot, the low oil pressure is exactly the same as the day I bought it almost 3 years ago.

If you look at an engine oil grade the first digit is the low point and the 2nd is the high correct?

I.E. a 10w40 has a low point of 10 and a high point of 40... Now is this a pressure or a temperature?

Kinda curious what grades of oils people pushing serious power use, surely they aren't still running the same 10w40 as the rest of the stockers out there...

Cheers,

Jarrod.

[senna_T]

The rating is for Viscosity (how thick the oil is) - its all about clearances. So the 10 is the viscosity when up to temp (thin & hot) and the 40 is the cold (thick).

Since you are still running the standard motor I'd stay with 10-40. You could look at going up to the 15-50 which is what I am thinking of doing, but it will take a little longer for the oil to get up to temp.

Keeping the grade of oil the same is important when it comes to clearances and keeping the motor running smoothly and quietly. As you increase the load on the engine (higher power) you need to make sure you use a high quality oil that is full synthetic, this will make sure that the oil can stay at its opertaing temperature for longer under high stress use.

that's a pretty basic explanation of how it works, and there is a much more in depth thread about oils here somewhere - but that should get you in the right direction. My opinion? Keep using the Nulon

[KIL-06L]

I just started using penrite's 10w40 seems good to me.

[Bad Apples]

The rating is for Viscosity (how thick the oil is) - its all about clearances. So the 10 is the viscosity when up to temp (thin & hot) and the 40 is the cold (thick).

No. This is backwards.

HowStuffWorks "Measuring Motor Oil Viscosity"

Motor oil - Wikipedia, the free encyclopedia

http://www.racq.com.au/motoring_advice/about_your_car/car_factsheets/understanding_engine_oil_designations

multigrade engine oil weights - Google Search

Chris.

[senna_T]

Sorry about that! Hands up, I obviously only know enough to be dangerous!

[Bad Apples]

's cool.

I'd like to edit my post but I think there is a timeout thing.. feel free to delete my quote and just leave the links.

To the OP:

I use nulon 10W40 fully synthetic and change every 7500. I on a cold start the oil pressure is about 3/4 (375kpa). scale and at 2000 rpm cruising when warm it sits about 200kpa. this is OK.

at idle when warm it sits about 120kpa, which is marginal pressure when HOT (after a fang) it sits below 200 at about 3000rpm. this is probably not ideal. so for ideal delivery on start up Ipersonally would be looking for 5w (I live in tassie so it's a bit cooler here..) and to lessen the effect of high temp and oil cooler would be best but perhaps a 50W might be OK as an alternative.

so overall I should run a 5W50... but the only one I know of is mobil and it's expensive....

I believe the 15W40 factory recommendation is comprimise based on semi-synthetic and a comprimise with the ford australia contract.

Cheers,

Chris.

[bjc]

I run 10W40 Royal Purple in my xr6t and also did so in my supercharged ba xr8 when I owned it. No problems with either of them.

I also run it in my mower With the mower it had a little puff of smoke on startup in Brisbane weather but nothing on startup here in Townsville.

Mower hasn't chewed any oil either.

[RIP_HSV]

ive had two tuners and both said different things, one castrol edge 0/40 the other penrite 15/40!!

[mattyb]

After reading around for days now, I found this and thought it had the 'easiest' to understand way of explaining oils... Hope it helps.

Found @ http://www.upmpg.com/tech_articles/motoroil_viscosity/index.html

- When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Colder temperature. The numbers without the W are all tested at 210° F or 100° C which is considered an approximation of engine operating temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210° (100° C). The difference is when the viscosity is tested at a much colder temperature. For example, a 5W-30 motor oil performs like a SAE 5 motor oil would perform at the cold temperature specified, but still has the SAE 30 viscosity at 210° F (100° C) which is engine operating temperature. This allows the engine to get quick oil flow when it is started cold verses dry running until lubricant either warms up sufficiently or is finally forced through the engine oil system. The advantages of a low W viscosity number is obvious. The quicker the oil flows cold, the less dry running. Less dry running means much less engine wear.

Obviously, cold temperature or W ratings are tested differently than regular SAE viscosity ratings. Simply put, these tests are done with a different temperature system. There is a scale for the W, or winter viscosity grades and, depending on which grade is selected, testing is done at different temperatures.

If a motor oil passes the cold temperature or W (winter grade) specification for a SAE 15W and at 210° F (100° C) flows through the viscometer like a SAE 40 motor oil, then the label will read 15W-40. Getting the picture? Consequently, if the motor oil performs like a SAE 5 motor oil on the reduced temperature scale and flows like a SAE 20 at 210° F (100° C), then this motor oil's label will read 5W-20. And so forth and so on!

I can't tell you how many times I have heard someone, usually an auto mechanic, say that they wouldn't use a 5W-30 motor oil because it is, "Too thin." Then they may use a 10W-30 or SAE 30 motor oil. At engine operating temperatures these oils are the same. The only time the 5W-30 oil is "thin" is at cold start up conditions where you need it to be "thin." -

Edited 22/04/10 07:19 AM by mattyb