Penrite oil for track/road car with forged bottom end

[project.r.racing]

One thing to be wary of is that modern oils are generally very thin and may not be suitable for older engines like those used in the NA and NB 5's.

Not entirely true, the 'thickness' of the oil has no correlation to if it is a new style of oil or old style.
The oil burning or leaking is due to other factors in the production of the oil. Depending on what base group it is blended with.

What I meant was that most oils made today for modern designed motors are 0-15W or 5-15W, whereas the older designed engines require a thicker oil in terms of weight, a 10-50W or even up to 20-60W or for some a straight 50W or 60W oil depending on application.

It's pretty easy to walk into a shop and just grab a nice shiny package of synthetic oil and find it is totally wrong for your motor after throwing it in by not paying attention to the weight of the oil on the package.

I'm sure plenty of people with older cars have thrown the wrong oil in them and wondered why it didn't do as promised in the marketing.

that is true. but the weight on the packaging is also very far from the truth for the real viscosity of any oils.

a mineral 10W30 from 1994 is completely different from a synthetic 10W30 from 2004/2014. the viscosities at air temp, 40 degrees and 100 degrees are all different.

a mineral 10W30 from 1994 is about the same as a synthetic 5W40 from 2014. if you read any data sheet available from the manufacturer of the oil, you'll soon be able to compare what is right and what is wrong for engine.

[sailaholic]

How do you get the data sheet for the viscosity at time of build for the engine though.


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[RS2000]

a mineral 10W30 from 1994 is completely different from a synthetic 10W30 from 2004/2014. the viscosities at air temp, 40 degrees and 100 degrees are all different.

The SAE classifications haven't changed in that time. They both will have a viscosity within the specified SAE range.
eg. for any 30 weight oil, viscosity at 100 deg C will be between 9.3 & 12.5 cst.
They might be at either end of the scale though.

Cheers

[ED_MX5]

Following on from RS2000-
Basically, the 'REAL' viscosity of oil is measured in cst.
the 10w30 spec is just a retail front. So take a 15w oil.
In cst, a 15w oil in one brand could be closer to a 10w oil in one competitors brand, or a 20w compared to yet another oil.
Regarding suitability for older engines, they make quite a few thicker synthetic oils compatible with older designed engines. The problem that arises is that with old, un-restored engines that still have the original seals, a newer grp4 ester based oil will eat the seals much like ethanol in petrol. Grp4 oil also is naturally a cleaner, so sometimes a little smoke being emitted for a few weeks to a month after swapping to a true full synthetic oil is natural. It is cleaning out all the deposits left by mineral oil.
However, they do have another form of synthetic that is called grp3, it is oils biggest secret.
What they advertise as full synthetic on most affordable synthetic is grp3. Grp3 oil is actually a mineral oil broken down and modified so much down do molecular structure that it is no longer a 'natural' product. Thus is allowed to be called a synthetic. On a side note, there was a big law suit against Castrol years ago from Mobil regarding this. Mobil calling fowl on Castrol for modifying mineral oil when Mobil oil was Ester based. Tests were done and the Castrol oil outperformed Mobil. So they let the classification stand. Anyway, a grp3 oil being mineral based will not damage the original seals in an engine. But as soon as you rebuild it and replace all the seals, which are now of different compound, you can transfer to a grp4 oil which is ester based. I have a 1972 Ford Escort Racing car, Fully rebuilt, running ester based Penrite racing 15w40. No leaks, No burning, No problems. Ester based oil can tolerate much higher heat before breaking down, additionally has much much higher film strength, a lower pour point and holds it's viscosity for much longer than conventional oil. On a track day, an mineral 20w50 after 20 laps is more like a 5w30. A synthetic oil will still be 20w50.
Hopefully that covers it, let me know if I missed anything.

[project.r.racing]

viewtopic.php?f=29&t=31490&p=652055&hilit=5W40#p652055

[ED_MX5]

True, one missed point is pour point.
cst is important in setting the viscosity. Assuming same cst range in mineral and synthetic at 40 and 100. the mineral 10w will be sludge at 0 degrees, a 0 grade oil will still flow well. Try this, ask a mate who has a 10wsomething mineral oil, ask for just a small sample. Then do the same for a 0wsomething synthetic and stick them both in the freezer for a little while, the 0 grade will keep sloshing around in the jar for quite a while. So yes, on basic stats some mineral and synthetic may appear the same. But are in reality quite different.

[ED_MX5]

Probably worth noting, as I forgot to mention.
Mineral oils are usually based on the hot side, and modified to still flow when cool so as not to induce wear upon start up. Inversly, most synthetic oils are based in the cool side and modified to work properly when hot. Weird and useless fact for the day...

[project.r.racing]

So yes, on basic stats some mineral and synthetic may appear the same. But are in reality quite different.

Isn't that what I posted? And got shot down on SAE rating not changing?

[ED_MX5]

You are very close, the sae doesn't change. Pour point is separate. so an sae from 1985 is same as sae from 2014. The sae simply is a common reference point so most people can just say, I want a 10w30 and know what they are getting, instead of trying to remember stats like I need an oil from x cst to x cst with a pour point of x and a base stock of x with a vi of x. So they work out what is best for most people and use a generic label for the masses. Its the finer thins like pour point, flash point and viscosity index that make the changes. Plus a few other odds and ends here and there. Make sense?

Please in no way view this as having a go btw, I am simply trying to help.

[project.r.racing]

Yeah I'm not saying SAE has changed. Dont care for a rating system that directs people the wrong direction.

I'm saying a mineral 10W30 from 1994 is nothing like a syntheitc 10W30 from 2014. The numbers on the bottle are the same, but the oils are very different.

[RS2000]

Yeah I'm not saying SAE has changed. Dont care for a rating system that directs people the wrong direction.

I'm saying a mineral 10W30 from 1994 is nothing like a syntheitc 10W30 from 2014. The numbers on the bottle are the same, but the oils are very different.

True in lots of ways. But their resistance to flow (ie. viscosity) which is very important, is similar at the selected temps of 40 & 100 deg C.

I wasn't trying to shoot anyone down, just adding more info.

Cheers

[Apu]

Gee...all this has flown over my head. This is kind of like gold plating electrical circuits...

[ED_MX5]

Yeah I'm not saying SAE has changed. Dont care for a rating system that directs people the wrong direction.

I'm saying a mineral 10W30 from 1994 is nothing like a syntheitc 10W30 from 2014. The numbers on the bottle are the same, but the oils are very different.

True in lots of ways. But their resistance to flow (ie. viscosity) which is very important, is similar at the selected temps of 40 & 100 deg C.

I wasn't trying to shoot anyone down, just adding more info.

Cheers

Fully agree, no offence meant. Just wanted to clarify info.
As long as you ask someone in the know, or do some research though. New oils will be quite beneficial to some older cars. As with any oil, old or new, the right information is key. It's still very easy to use an old oil with an old car and get it badly wrong.
But your right, viscosity is not the be all and end all.
After all, if you just relied on viscosity alone and no chemicals, you could use heaps of oil.
Like a 5w30 is same cst as 75w90 is same as dex3 is same as hydraulic 68 etc etc. Weird hey.
Oil is a strange world.

[davekmoore]

Blimey, I thought I'd asked a simple question! The good news seems to be that no-one has suggested my decision was wrong.

Just to turn this discussion around a bit, I'd be interested to hear opinions on Redline Water Wetter and/or similar products. On the face of it, for $30 or so, you just would?

[ED_MX5]

Awesome stuff. As you say... $30 just do it.
I use in in my track car. Works for me.