P38A Probably been done to death many times.. but.

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DanClarke

DanClarke

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The "THOR" 4.6 V8 is a 60's engine bored out with a fancy injection system stuck on top, but everything else is OLD, OLD, OLD. These old engine designs with non-roller lifters(?) like ZDDP in the oil I am told.
Cat's hate ZDDP (tried my cat on a spoonful and it said "NO!").
Given that Cat's are cheaper than engines and major engine rebuilds what does one go for?
Duckhams-Q with ZDDP of 1100 PPM? Or:
Fuzz Townsends "Heritage" 20/50 with ZDDP of 1300PPM. Or:
Penrite Classic 20/50 with ZDDP of 1080PPM. Or:
Quality 10/40 oil as per handbook with (no ZDDP).

I know LR says 10/40 in the handbook, but this is my "somewhat out of warranty" 20 year old car, so let's be sensible and assume they wanted 10/40 low/no ZDDP to prevent CAT burnout claims as it was all touchy-feely environmental stuff (and I don't care about that element of it).
What's worse, a knackered CAM etc. or a knackered CAT?
I really would appreciate @wammers and @Henry_b 's input here because they know engines and I respect the opinions of folks that do this stuff for a living.
 
My V8 is at 130k and runs Valvoline VR1 20w50.




This is RPI's opinion on it "specialised rover V8 engines"




The Thor V8 still has the SU carb cutouts in the Valve covers!

the inside is the same, apart from the oil pump which is crank driven as apposed to the dizzie driven one of yesteryear.

The Flat tappet cams NEED ZDDP its a given.
 
I use valvoline also
Regards 20/50 vs 10/40, 10/40 wasn't around in the 60's and was only used on these engines because it marginally helped with mpg
 
Early oils had Zinc in them to cut down heavy contact wear. Cams ran in the centre of the tappet. Cats do not like Zinc so it was removed. These days cam lobes do not run in the centre of the tappet they run slightly off set. This causes the tappet to turn as they are lifted, evening out wear across the surface. All Land rover or anyone else had to do theoretically when Zinc was removed, was re-space the cam lobes. How a camshaft is fitted and the initial start up and bedding is critical to it's longevity. The most critical part of running an engine is the startup before oil pressure rises, when oil has drained from moving parts. Thinner oils are circulated quicker so this critical time is reduced to a minimum. An incorrectly fitted cam shaft can be ruined in the first five minutes after initial start up if it is not done correctly.
 
Thanks to all for your advice (@wammers , @Henry_b , @kermit_rr ).
If I understand the situation correctly, LR didn't do any of these sensible things to prevent wear and the engine is still as originally designed in this area. I think I will go for a ZDDP "included" oil (stuff the CAT).
 
DanClarke said:
Thanks to all for your advice (@wammers , @Henry_b , @kermit_rr ).
If I understand the situation correctly, LR didn't do any of these sensible things to prevent wear and the engine is still as originally designed in this area. I think I will go for a ZDDP "included" oil (stuff the CAT).
Click to expand...

I think you may find that camshafts changed from the added Zinc 3.5 era to allow for the none Zinc oils.
 
DanClarke said:
Ahhhh....... did they? I didn't know that Tony. This infers that the recommended quality 10/40's are fine then?
Click to expand...

I would say so. Fully synthetic oils are far more tolerant of heat than 20w 50 will ever be. Don't forget that to try and cut emissions engine now run a lot hotter than they used to. 74 degree stats were normal at one time when 20w 50 zinc oils were used. Stats now run in the 90s so a lot more heat to get rid of. Older spec oils don't like that much heat.
 
The Cams in regard to materials stayed the same regardless.

It is the Flat tappet itself that wears to the Cam usually dishing the tappet and wearing the cam lobe flat.
tappets are one of the most stressed and poorly lubricated surfaces in an engine. The case hardened cam shaft lobe is dragged across the hardened lifter face under great pressures from valvesprings and valvetrain inertia. It's high-shear wear point,

34136352.jpg


ZDDP is required and an Oil like VR1 can easily cope with the heat the RV8 puts out.

Halfords Classic I wouldn't be inclined to use etc etc. :)
 
Last edited:
Henry_b said:
The Cams in regard to materials stayed the same regardless.

It is the Flat tappet itself that wears to the Cam usually dishing the tappet and wearing the cam lobe flat.
tappets are one of the most stressed and poorly lubricated surfaces in an engine. The case hardened cam shaft lobe is dragged across the hardened lifter face under great pressures from valvesprings and valvetrain inertia. It's high-shear wear point,

34136352.jpg


ZDDP is required and an Oil like VR1 can easily cope with the heat the RV8 puts out.

Halfords Classic I wouldn't be inclined to use etc etc. :)
Click to expand...

Think tests were done on some so called classic oils, the Zinc content was far below the original specs. Think the Halfrauds classic oil passed a tin of Zinc on it's way out of the warehouse. :D:D
 
£60 an oil change is £30 - £40 more than I pay every 5000 miles for semi-synthetic. Add 2 cats to the cost and the ease of getting the cams out and tge sums don't add up to me.
 
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