Thread: Best oil to use

The 10w is great for start up..

It's the 50 bit that I'd want in the heat.

Originally Posted by ozscott

There is significantly more Zinc in the mineral HPR30 20w60 versus the synthetic HPR 10 synthetic.

I live in the same general area as Cannon. The thinner oil let's the engine rev more quickly but I'm not convinced the old motors (by design as mine has done less than 40,000k) wear best on 10w (and 5w despite what dealers used to use is just too light in my view).
Cheers

But the 10W and 5W are just indicators of the cold flow characteristics, they have no bearing (no pun intended !) on the hot viscosity.

A 5/10/15/20W-40 will still be an SAE40 oil at 100*C.

And FWIW ZDDP (commonly called zinc) isn't the be all and end all as far as AW and EP additives go, but it's bloody (cost) effective.

HPR10 0.108% Zinc versus HPR30 0.157%.

Cheers

I know what you mean Rick...mine is running way cooler than your average D2. From a cold start you can tell the oil is thicker but I warm it and drive accordingly.

So you would prefer say 15w50 if Penrite made such an animal (I think the 3.9 was 15w40 and I cannot see, apart from emissions, peak power and economy that the 4.0 has any changes to justify the thinner oils. I prefer in QLD at least 50w in summer. It's All a compromise I suppose. Perhaps I should run 10w50 in winter and 20w60 in summer. Cheers

I see they still do 15w60 HPr15. That might be the best allrounder given you aren't that excited about Zinc Rick...

Cheers

Wow...they do a 10 10ths 10w60 (big cost too).. Cheers

Interestingly Penrite describe HPR10 as for use in modern multi valve OHC engines and HPR30 for engines (by omission not modern) and where high load conditions are present such as for towing. Cheers

No, zinc is good, but in modern oils additives like boron and tin napthenate work really well, but they are more expensive than ZDDP.
The problem is you don't know what has or hasn't been used, so Penrite have found a clever way to market their anti-wear characteristics by touting "we use zinc".

Formulations change as regulations change.
Way back in the mists of time, my favourite engine oil was a di-ester synthetic that had heavy doses of lead napthenate.
It was brilliant for wear. Interestingly their CV joint grease had high levels of lead in it too, as well as moly and graphite.
In the late eighties it was used by most F1 teams as it was the only CV joint grease that would last a race behind the turbo engines of the time.
Unsurprisingly we don't see lead derivatives used anymore.

The old rule of thumb used to be that 1200ppm ZDDP is a good level for flat tappet cams. If using lower levels, I'd like to know what else is there.
Using a diesel oil was once a good way to mitigate cam wear, but the HD diesel oils are dropping their SAP's levels right down now, to the point that the latest API CK-4 formulation in the US is being blamed for wear problems in Ford diesels.
Ford are recommending not to use oils meeting the latest spec except Motorcraft (their own).
This is creating a bit of a scandal there as the new specs are all supposed to be backwards compatible and have less wear than previous blends.
Practically it hasn't always worked out this way. We had the situation here back in the late '90's/early 2000's where the Japanese manufacturers wouldn't allow the latest US diesel oils to be used as one 'update' had lowered the metallic ash levels, particularly calcium, and this had accelerated cam wear in some of their diesels (sound familiar ?)
Calcium compounds are one of many dual purpose additives, primarily used for their detergency, but equally used as an anti-wear component.
That one took the Japanese manufacturers ten years to get over even though a hastily revised update of the spec reversed the issue, they were pretty gun shy of new/updated blends meting more modern US specs for a long time and wouldn't approve them even though they were actually better oils.

I don't see the need to go above an xW-40, and while an xW-60 is great for fuel dilution issues or endurance racing, it's overkill in a road going engine. (yes I know BMW specced it in some of their M Series engines )
You're just giving away grunt, relatively there's too much parasitic drag with the heavier oil, and it puts big loads on oil pump drives too.
Put it this way, I think having 1200+ppm of ZDDP in a 10W-40 oil is better than 1000ppm of ZDDP in a 10W-60 all things being equal. The problem is that additives are synergistic, and the blender could be using other, more expensive additives that combined actually work better than straight up good old ZDDP, but only they know this, so the safe thing for us end users is to grab the oil that says it has 1200ppm of ZDDP in it, then we know we're covered.

Actually, nothing overcomes fuel dilution of oil!