Penrite 10W-70 synthetic 'SIN' engine oil.

[Hemi6]

Hi guys. Long time reader, first time poster.

I've got to do an oil change on my BMW 535i (the one mentioned in my signature) and I currently run Castrol Edge 10W60, and the factory sticker under my hood specifies 10W60 oil be used in this car.

I was at the auto parts shop on the weekend, and while reaching for the Castrol 10W60, I spotted some bottles of Penrite 10W70 (Penrite is a local Aussie company here, you may not have it in the US). I thought about using it, for three reasons:

1. the 10W "cold" number would be good on cold starts, as this would be thin enough to allow quick circulation around the engine when it first starts up?

2. The 70 viscosity number would be good because BMW V8s have a very high "normal" operating coolant temperature of 110 degrees C, and these engines always run *very* hot, even from factory. If the oil only thinned down as much as a 70 viscosity oil when hot, then this would be good because it would still provide a good thick lubrication film and would not thin out as much under the high temps. Plus, there are no oil coolers in the car at all, so the oil has to just suffer the high heat.

3. This engine has covered 250,000 kilometres and it is 13 years old and never rebuilt. Tolerances between internal parts are probably worn larger than they were 13 years ago. So maybe using a slightly thicker oil would help boost oil pressure and be better for the engine, considering how much wear there probably is inside it?

Are my three points above correct? Or is my logic wrong or am I missing something very important in my considerations about using this oil? I can get no help from the BMW community, because they believe that they must stick to what is written in their owners manuals, and never change viscosity. But my car has travelled double the amount of mileage theirs has. I am being told by owners to put really thin oil in the engine (10W40, 0W30) because thats what everyone else uses. But in an old engine like mine, I think a superthin oil would be a bad thing?

Oh, some info about my situation-
*I drive my car fairly hard. I'm no grandpa.
*I have never had any mechanical problems with the engine. Always smooth and always reliable.
*My driving consists of 50% city stop/go and 50% highway every day.
*We are just coming into summer here, and the temps are already getting high outside (100F/40C so far)
*I love my beemer and I want to make sure the oil I use will contribute to further longevity of my engine. Even if that means changing viscosity as it gets older, to compensate for wear & tear.

Can you please give me some feedback?
Here is the webpage for the Penrite oil in question: http://www.penriteoil.com.au/products/motor-oil/sin/sin_engine_oil_10
And they seem to have a very well written FAQ page as well, which was suprising:
http://www.penriteoil.com.au/faq.php

Thanks guys

 

[Petrou]

You know from what i see and read, i would use it. We dont have anything like that state side but i wish we did, but ya i would totally use it without worry especially with that mileage. i think it looks pretty good

 

[Doug Hillary]

Hi,
Hemi6 - Welcome to BITOG - enjoy

What lubricant are you using now (Castrol 10W-60?) and what lubricant(s) has the engine been on for the major part of its life?

 

[2003f7]

 

[Petrou]

Sorry i didt realize that was your first SSOOOOOOOOOOO!!!!!!!!!

 

[Hemi6]

Hi guys. Thanks for your responses. Thats a [censored] of a welcome

The car in question has always had Castrol 10W60 in it. It was bought in 1996 from our local BMW dealership, and they serviced it until I bought it-

The history goes something like this:

BMW dealership uses BMW brand 10W60 from very first oil change, up til 220,000km. I then buy the car and use Castrol 10W60 (basically same as the BMW oil, but different label on bottle) up til now, when the odometer reaches 250,000km.

Thats been the history of the oil for this car really.

I drive 80km per day (1.5 hrs per day), 5 days a week. its my daily driver.

 

[JohnBrowning]

Penrite makes a good oil I have recomened it in years past because I used it growing up in Europe a few times. Yes we used to have PEnrite avialbe int he USA but I have not seen it for some time now! I would never put a 10W70 in anything I owned. I think a 5W40 is more then enough especialy with a good synthetic. You have to put a lot of VII's in when you start doing the 5W50 or 10W60 thing and it is just not needed! It really is a waste. I am not saying you should go out and get some 0W20 and fill the old girl up but really a 15W50 or 5W40 or 0W40 in a quality synthetic will not only do the job but will more then likely do it better. I thought Delvac-1 5W40 was priced ok in OZ? If so I would go with that.

 

[Doug Hillary]

Hi,
Hemi6 - I largely agree with John (JB). It depends on what the recommended viscosity is fo your engine - I used Delvac 1 5W-40 in my Z3 2.8 with great results up here in the hot Tropics

In your case it raises the question of "why change a good thing"?

Castrol's 10W-60 is at least the equal of the Penrite lubricant. It has a formidable record in race engines and gearboxes etc that can be traced back for over 30 years!

And look at your engine today - it has done the "wear minimisation" job well by your account - why change??

 

[Hemi6]

Why change a good thing- absolutely.

I downloaded the data sheets for both the 10W60 Castrol and the 10W70 Penrite oil, and looked at the CST* values.

*(the CST value is the centistroke value, and is the measurement of a fluid's resistance to flow (the viscosity). Its calculated in terms of time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the CST (centistroke) value is, the more viscous/thicker the fluid is.)

And the 10W60 Castrol I currently use is 24.0 centistrokes @ 100C / 168 CST @ 40C.
The Penrite 10W70 is 29.2 centistrokes @ 100C / 215 CST @ 40C

So there's a fairly large difference in thickness at 100C and 40C temperatures between the two oils. Enough to make me rethink the 10W70 and stick with the Castrol 10W60. If its enabled the engine to survive to 250,000km up til now, I think it would be wise to just keep using it.

Having said that, the Penrite oil is still really good stuff, and if I had a use for it, I would use it. But I'll continue with the Castrol 10W60.