Penrite

[Gresley]

I've always used Millers or VR1 engine oil in the Stag, but last time I tried Penrite HPR 15 15w60 which is apparently full synthetic. The Stag seems to love it - runs quietly, oil consumption has dropped a little etc. I'm a little nervous of putting unknown (to me) oil in my engine so was wondering if anyone else uses it? Have you had good results? Or is it best to go back to one of the others?

Hmmmm...!

Brian

[martin]

One thing worth trying Brian, leave the old girl overnight, then take off a cam cover before starting, and see if there's a pool of oil around the cam buckets. Synthetics have been known to drain down and leave you with a dry start. If there is a small pool, you're laughing. Martin.

[badenstag]

Hi Brian,

I use the classical Penrite 20W60 which is a mineral oil. I wouldn't use a full syntetic oil.

Regards
Gerd

[ChasR]

I am sure most the issues stem from people using too thin a grade of oil rather than them being a fully synthetic themselves. I mean, Valvoline VR1 has some very modern oil specifications to it (more modern than any classic Millers product) hence that should leak (if you believe the theory that the older specced stuff has seal swellers etc. in order to help keep the oil in).

I know in two cars of mine this has been the case (A Porsche 944 S2 which had Mobil 1 0W40 over 10W40 or 15W40, and another similar scenario with a friend's Fiat Turbo coupe (I believe they take a grade closer to the Stag (many run them on 10W60 with good results); A friend of mine used to swear by the aforementioned oil (0W40 Mobil 1) despite the manufacturers reccomendations being vastly different for his car (Halfords et. al having it on offer most of the time did not help matters).

[Gresley]

Thanks folks.

Martin - thanks for the tip, I will whip one off at the weekend and have a peep inside.

Gerd- I think this one will be OK as it is a fairly high viscosoity, I'll do as martin says and find out!

Chas - Yes I think so too, as you say a lot of very modern oils are really thin.

Still hard to decide though, I have no long term experience of a different oil!

Brian.

[Hughesy]

Penrite HPR 15 20w-60 is a full synthetic and it would be interesting to learn its ZDDP content. ZDDP greater than 1000 PPM is recommended for older designed flat tappet engines such as the Stag.

I have been using Mobil 1 V-Twin 20W-50 (4T oil) and am very happy with the performance and oil pressure.

I have also used Castrol Edge "Sport" 10W-60 in the past.


Mobil 1 specify considerably higher ZDDP levels for flat tappet applications. Here are the values for comparison:

Castrol Edge Sport 10W-60 ZDDP 1000 PPM Phosphorus 0.09%
Castrol Edge 10W-60 ZDDP 1100 PPM Phosphorus 0.10%
Mobil 1 15W-50 (designed for flat tappets) ZDDP 1300 PPM Phosphorus 0.12%
Mobil 1 V-Twin 20W-50 (4T oil) ZDDP 1700 PPM Phosphorus 0.16% *

* Motorcycle (4T) oils are not subjected to the compulsory reduction of ZDDP and Ph.

[ChasR]

Hmmmm, I did consider using Mobil 1 15W50 or 10W60 at one point (The Porsche runs on the latter, but that can trash oil when worked hard ).