How Bizarre-3.9 uses less 15-40 than 10-50

**PhilipA** · 11th September 2009, 07:20 PM

On my trip to the Kimberley in my 92 RRC 3.9 V8 I did 3 oil changes , one at Derby after about 7KK (5 L shell helix plus 15-50 plus 1 L of valvoline 15-40 Engine Armour), one at carnarvon after 5KK ( Valvoline 15-40), and one at Buderim after 7KK.

My car has always recently used about 1litre ( Ie just above ADD) of Shell Helix Plus 15-50 per 5KK. Most of this goes down the valve guides as with new heads on it used almost nil. I refitted my old heads after recondition and modification including teflon seals on the inlets and no seals on the exhausts and shortened inlet guides.

At Carnavon I changed to Valvoline 15-40 , hoping to get a bit more economy , and the fact I couldn't get Shell as the servo was out of it.

Strangely , the oil consumption then fell to about half of that using Shell 50 weight. On changing at Tewantin after 7KK the dipstick was still at 50% , having been about 2MM above full on the change. I definitely did not expect this as I was concerned that my oil consumption would increase significantly with the 40 weight oil.

In addition the engine "feels" happier with slightly improved performance, so much so that my SWMBO noticed it.
So in my case anyway The V8 seems to love Valvoline 15-40 Engine Armour and if your V8 is in good condition, I would not hesitate to use the thinner oil.

**PAT303** · 12th September 2009, 10:15 AM

I ran the same Penrite diesel light oil in my 3.9 as I used in the Tdi and IMHO it's better for V8's to have a bit more detergents go through them.It ran like a clock for 4 years. Pat

olbod · 12th September 2009, 10:33 AM

I only ever use Penrite HPR Diesel 15 oil in my 3.5 V8i.
Seems to love it and hardly ever needs topping up.
I give it a full service every 8 thou and the oil looks as clean as the day it went in !!
I put only penrite in the other boxes and diffs in the Disco.
I use Penrite HPR 5 in me John Deere ride on.
Cheers.

**Grimace** · 12th September 2009, 11:20 AM

I just switched from Magnatec (10w40) which i foolishly used all the time, to Edge Sport 25W-50.

All I can say is the magnatec was crap in comparison, the engine note was better after the edge went in, the oil leaks have dissapeared.

Also the magnatec aged very fast and was almost like water after 6000ks.

So I personally wont be running a 40 weight oil in my rover v8 ever again.

**RoverP6B** · 12th September 2009, 02:13 PM

The weight of the engine oil is dependant on the type of oil pump that is fitted. With those engines running the camshaft driven oil pump, a minimum 20 weight oil is advised....ie 20W-50.

For engines fitted with the crankshaft driven oil pump, which is much more efficient than the above design, a 10 weight oil is quite satisfactory,..ie 10W-50.

Ron.

**RRV80** · 13th September 2009, 01:33 PM

i use the casrol edge sport 25W-50 in my 3.9 and it loves it, have tried a few different oils in it but it prefers the 25w-50, doesnt seem to use any oil between oil changes (it just leaks out the valley

) its done 250,000km now btw

**Slunnie** · 13th September 2009, 01:49 PM

Originally Posted by Grimace

I just switched from Magnatec (10w40) which i foolishly used all the time, to Edge Sport 25W-50.

All I can say is the magnatec was crap in comparison, the engine note was better after the edge went in, the oil leaks have dissapeared.

Also the magnatec aged very fast and was almost like water after 6000ks.

So I personally wont be running a 40 weight oil in my rover v8 ever again.

I noticed in an old Toyota AE86 Sprinter that I had, that Castrol GTX2 used to also drop a lot of pressure, particularly at idle after about 6-7000km. I stick with Mobil 1 these days. In my racing days found Shell to be excellent (at least for 2-stroke lubes and hi octane fuels).

**Chops** · 13th September 2009, 02:13 PM

Originally Posted by Grimace

I just switched from Magnatec (10w40) which i foolishly used all the time, to Edge Sport 25W-50.

All I can say is the magnatec was crap in comparison, the engine note was better after the edge went in, the oil leaks have dissapeared.

Also the magnatec aged very fast and was almost like water after 6000ks.

So I personally wont be running a 40 weight oil in my rover v8 ever again.

I've found the same thing,, the Magnatec worked really well when the engine was new,, but now its done over 250,000k, its not so good,,used heaps really fast,, I've now changed to the GTX 20/50 (for "older" engines

), but it seems to be working well, and staying "in" the engine now. Its also quietened down the tappets somewhat,,

**Armadillo** · 13th September 2009, 07:17 PM

Originally Posted by Chops

I've found the same thing,, the Magnatec worked really well when the engine was new,, but now its done over 250,000k, its not so good,,used heaps really fast,, I've now changed to the GTX 20/50 (for "older" engines

), but it seems to be working well, and staying "in" the engine now. Its also quietened down the tappets somewhat,,

I'm running GTX2 20/50 too and has been great. It maintains good pressure and reasonably quiet.
Last oil change I changed to Calibre 20/50 -a caltex brand from Supercreep at about the same price point. It turned out be not too good

. Lesson learnt and back to the GTX2 today.

**Traco** · 14th September 2009, 05:04 PM

K-Mart 20w50 KMX oil, cheap as but also up there with some of the best, amazingly. Scroll down and see the write up by respected Sydney race engine builder Graham Russell about how good it performs in pushrod race and road engines and analysis of the oil by another oil company's industrial chemists. And in a race Mini the same oil has to service the engine, gearbox and diff at 8,000 rpm. Interesting point too about the shortcomings of synthetic oils in 1950s designed engines, like the Rover V8.

ausmini :: View topic - Oils aint oils....or are they??

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