Engine oil - 1984 8V

[simdel1]

I've been lead to believe that my car is running on 20W50. The small bottle of Miller 20W50 in the boot seems to confirm this. I've checked the owners manual and this seems to be ok. Besides, I'd imagine after 156k miles the bearing clearances will have opened up a bit!

Anyway, I've recently bought some Halfords classic 20W50 mineral oil (I was seduced by the old-school metal tin []) and I was wondering if anyone had any thoughts on this before I comit to the oil change?


Link to the product

 

[333pg333]

A 20w/50 mineral is fine for our cars no matter what many others think. There's no info as to the contents of this particular oil however. Look for ZDDP in the package.

 

[simdel1]

Apparently it has some ZDDP...whatever that is!

 

[944 man]

If its really Millers in the bottle then Id use the same product when you change the oil. 20W-50 is the ideal grade for your car and Millers make extremely good oil.

Is it mineral or synthetic? Good PAO-ester synthetic oils will provide the best protection and they last. People seem to think that synthetic oils arent suitable for the cars but in actual fact, its the common synthetic grades (5W- or 0W-) that are the problem. That said though, my old series one car didnt use a drop of Silkolene Pro 5W-, although my 2.7/3.0 engined car will do about 500 miles to the litre of the stuff! Alter the grade to 10W/15W and the consumption drops very quickly; but this will be the case, whether the oil is synthetic or not.

 

[simdel1]

Thanks guys. I figured that this question would divide opinion!

So far I've got a yes and a no. Does anyone else have an opinion before I toss a coin to decide whether to see if halfords will take the oil back?[]

 

[schambers]

Hi,

I Use 20W/50 In my Land Rover Series III and in my spitfire and it's brilliant (and it does have a terrific looking tin) BUT... It's really thick oil which is perfect for British Leyland engines with slightly larger engineering tolerances, I certainly would think carefully about putting it in a precision engine.

Simon

 

[944 man]

Im not sure that we have a yes and a no: I dont disagree with Pat and my post isnt intended to contradict his.


Simon

 

[robdimond]

I use 20W50 in my '89 S2 (Valvoline VR1). 20W50 is one of the right grades of oil for these engines, according to the manual.
I can't comment on how good the Halfords stuff is... but I think as long as you change the oil often, surely will be fine.

 

[944 man]

Thisd all be a little clearer if the OP stated whether the Miller was mineral or synthetic. Ive presumed that it was synthetic, hence my suggestion that you continue to use the same product (because [1] millers is excellent oil [2] its probably sythetic and its better not to mix). 20W-50 is certainly the grade that I would choose.

 

[Jonny944CS]

My ten pence worth:

The numbers (20W/50) denote only the oils physical properties, without any information on their performance characteristics (Synthetic %, protection, detergents etc.). These can vary widely between different manufacturers of the same multigrade. A base 'mineral' oil with no modern synthetic additives is unlikely to be great in terms of performance (the Halfords recommended oil change interval of 2-3000 miles could be a clue here).

When talking about a multi grade oil, the '20W' or winter number denotes the oils flow properties when cold (measured at 0°F) . For example, at given viscosity a 0W oil would be at -30°C and a 20W oil would be at -10°C.
Variations in this number will tend to affect the following aspects of the engine:
-- Cold cranking friction >> Starting efficiency
-- Pumping rates >> Hydraulic tappet filling + Camshaft/lobe lubrication
-- Drain back rates > Sludge collection

The second number (50) refers to the oil's flow properties at 100°C.
Variations will tend to affect the following:
-- Running friction >> Fuel consumption and Peak power
-- Consumption rates >> Flow past piston rings and (to a lesser extent) valve guides

IMHO from an optimum performance standpoint, and assuming a healthy engine, I would argue that 20W/50 is a little thick for our UK climate and normal 944 usage.

If you don't live somewhere hot and spend most of your time with a normal oil temp (i.e. not 100°C plus), I would be inclined to go for a good quality 10W/40 e.g. Millers, Mobil, Shell etc.
Or at the very least, stick with the Millers synthetic 20W/50.

 

[simdel1]

Apologies Simon. I've just into the boot of my car (I couldn't before, I was at work...) and checked what oil is actually there. Seems it's actually Morris 20W50, not Miller[&:]

Link to Morris product

I've had a look all over the bottle of the Morris stuff and on their website and I can't see any reference to whether it's mineral or not. However, their FAQ section has the following question:

1. Can I top up mineral oils with synthetic oils and vice versa?
Yes.The synthetic fluids (polyalphaolefins) used in engine oils are man made versions of mineral oil and are therefore compatible with mineral oils. In semi-synthetic formulations, mineral oils and synthetic oils are part of the same formulation. The only downside here is if you top up expensive synthetic oil with mineral oil you will be effectively diluting the advantages that such an oil will provide (good cold start, good high temperature performance and longevity).

So at a guess, the product could be synthetic but they don't seem to think there's a problem mixing synthetic with mineral...

 

[944 man]

Neither were any of my posts intended to sound short either, sorry.


Simon

 

[944 man]

They do 'mix' together, but its far from ideal: Id avoid it where possible. I havent heard of Morris oil - its a shame that it isnt Millers though... I think that the Halfords oil will be perfectly alright changed annually/every 6,000 miles.

 

[333pg333]

I wasn't disagreeing with anyone either...although I've been known to contradict myself. []

In general I would use a 20w/50 for our cars on the basis of what the factory manual suggests, but also what the consensus of many in the field experts hold.
Having said that, I live in a warm to hot climate and in general want racetrack protection. We use a 25w/60 in our track cars but if I was in an English Winter
even I could be convinced to move to something lighter in weight like a 10w/40.

 

[Jonny944CS]

Bit of a gray area this oil business... [] I think everyone has made valid points and you could make a good case for each of the arguments. The choice, in the end, comes down to personal situations and priorities.

The factory manual could be accused of hedging-its-bets somewhat and is open to some interpritation. But compared with many owners manuals, I find the bar charts very informative.

In contrast, if you take a fairly recent press release I found , without any pinches of salt, all cars from 1984-on should be running fully syn 0W/40. I'm not sure that would go down too well with all engines still running from that 27 yr period!

Obviously engine condition is a significant factor. If your piston rings and seals aren't what they once were then perhaps a good quality 20W/50 is a more prudent option in the long-run.

 

[simdel1]

ORIGINAL: 944 man

Neither were any of my posts intended to sound short either, sorry.

Don't worry Simon. I assumed that you were just keen to get all the facts so that you could advise me properly []


Thank you to everyone else who has given me their thoughts too. I really appreciate it.

I think i'll sit on this one for a few days before making a decision. On one hand, the UK isn't cold and the 944 engine is a 'precision engine, so a lighter weight (and possibly semi/ful synthetic) 10W40 sounds like a good idea. On the other hand, the user manual defined range for the 20W50 looks sensible (how likely is it that I'll be driving it when it's below freezing...) and after 156k miles, the bearing clearances and piston ring clearances must have opened up a bit so maybe the 20W50 is appropriate. It seems to be running just fine on it at the moment. And, most importantly, the Halfords classic oil comes in that lovely retro-feel metal tin...


Decisions decisions[&:]

 

[Jonny944CS]

ORIGINAL: simdel1

Apparently it has some ZDDP...whatever that is!

If you are interested, I found this paper to be very well written.

The viscoscity details are specific to a Corvair, I would say the 944 is one group higher on the SAE scale (page 3) for normal use. I could be wrong, others clearly disagree. But it contains lots of details about all the strange letters found on oil containers.