oil choice for a v8

[landkeeper]

my hybrid has a primative 3.5 carbed engine ,the oil pressure drops right off at tickover when shes hot to the point when the oil pressure light comes on at about 8oo revs (tickover) she has about 10psi per thousand revs when running it has 20/50 in at the moment ,before i possibly start changing oil pump gears would i be better to try a thicker viscocity oil

thoughts??

[mickeyw]

I use 20W50 in my RRC 3.9, recommended for older V8s.

I used to use 15W40 until it was suggested the 20W50 would be better. I can't say I can detect any difference in running or tappet noise, but the 20W50 is cheaper at my local factor's.

[FridgeFreezer]

Oil pump gears are not a difficult job to do, although there can be other factors like the oil pump cover surface being scored/pitted and the pressure relief valve the same. You can use some fine emery paper on a bit of something very flat to re-flatten the face of the pump cover, I'm sure Bull Bar Cowboy or someone posted the info and maybe even piccies in the tech archive.

[Bowie69]

Yep, it's*HERE* (have the thread on bookmark atm!)

[Boothy]

It could be what is known as knackered and may need a lot more than oil pump gears, it may need big end bearings, main bearings, camshaft bearings, rocker shafts and rockers, and then have a good luck around for wear, but try some good old 20/50and hope for the best.

Questions are, does it rattle and smoke a bit, and has it done a million miles ???

Good luck

[flatback90]

http://www.devon4x4.com/forum/general-enquiries/oil-pressure-in-a-3-9v8/

see here mate

[landkeeper]

no it's not knackered smokey rattly or wheezy and its a gold seal job , starts first pop and has loads of power just appears to hev low oil pressure at tickover when hot

[Hybrid_From_Hell]

Valvoline VR1 racing oil,

Its the best for a early V8, its what I use and I even

won over BBC (not an easy stunt ) who used Magnatec

but then agreed VR1 was a amazingly noticeable better oil

And its not a fortune

Nige

[landkeeper]

thanks i'll go shopping for some of that and give it a whirl

[mateyboy]

Silkolene PRO R 15w-50 , Silkolene PRO S 10w-50

Motul 300V 15w-50

Mobil1 15w-50

if using for competition or giving it some stick, fully synth Mobil 0w-40, Castrol RS 0w-40, Amsoil 5w-40 or Fuchs Supersyn 5w-40 the new rangerovers use 0/40 or 5/40

[Bowie69]

if using for competition or giving it some stick, fully synth Mobil 0w-40, Castrol RS 0w-40, Amsoil 5w-40 or Fuchs Supersyn 5w-40 the new rangerovers use 0/40 or 5/40

They might, but they are completely different engines, based on a design probably 40 years younger.... not what I would recommend for a Rover V8 in any shape or form.

A 20w50 works well in them, Duckhams Green gets my budget vote.

[Hybrid_From_Hell]

Silkolene PRO R 15w-50 , Silkolene PRO S 10w-50

Motul 300V 15w-50

Mobil1 15w-50

if using for competition or giving it some stick, fully synth Mobil 0w-40, Castrol RS 0w-40, Amsoil 5w-40 or Fuchs Supersyn 5w-40 the new rangerovers use 0/40 or 5/40

^^^

For older oil pump / non serp engines these will not be enough

Serp oil pumps are very very different, just to bear in mind

Even so I would question some of the above, esp for a comp engine (which mine as

as a JED unit) VR1 is a frankly amazing oil, recomended to me by 3 x engine gurus who know more about V8s than I'll prob ever forget

Nige

[mateyboy]

I run a 110 CSW with auto box, 3.9 pre serp with 10/40 semi synth, it's happy as Larry, and a 4.4 RR 0/40 fully synth, that's as happy as a sand boy! Just go for the best spec that's cheapest.

[101sean]

As others have said, synthetics or semi synthetics in an early V8 (pre serp) are a waste and will have it running like a bag of nails in short order. Stick in a decent thick syrupy 20W50 and your engine will thank you, the V8 runs on quantity, not pressure.

Is you're oil light flickering (try another sender) or are you looking at a gauge (many won't read low enough for a V8 at idle! )?

If the above or new pump gears, pressure relief valve etc doesn't cure it, you have a worn engine problem.

[mateyboy]

so all in all, the poor chaps answer is as clear as mud!

[Hybrid_From_Hell]

Erm

No not really

There are two types of V8 simply (variants but 2 types)

Serp, and pre serp, and the 3.9s have a foot in both camps

Pre serp engines (as the poster has) have weak oil pumps, which need viscosity and volume

to drive the pressure, wear on these units is often both the gears on mesh faces and also

the alloy casing they spin in. The gears can be replaced (and will often see a jump in pressures

as a result, but the casing wear in impossible to fix other than a new less worn timing cover

with integral case

The base plate also suffers from ident wear, again seeing a pressure drop, refacing the

base plate to remove gear marks helps, as does high pressure relief valves etc, but none of this

is worth diddly with modern thin oils even if fully synethic, a clue is a rattle at start up

which is lifters oil drain, and the rattle goes on lifter re priming, the damage done in those

few seconds is underestimated by many

VR1 in a pre serp V8 is IMHO about the best you can get and reasonable money, its ultra high spec

and is recomended by many V8 specialists that I look to for guidance, thin oils of any fab rating

are really not suitable, esp if the engine has wear and several thousand miles on top.

The other really importnat thing about all V*s is the oil change frequency, its no good

shoving is a great oil for too long, change the oil and filter regularly, on my JED its every 3 months

and use a decent filter too, mine is a JED 4.5 but has the non serp front end hence all of the above

Serp engines have an entirely different pump sytem, and operates totally differently, and the 2 types should never be confused

Nige