On what basis do you recommend which oil to use ?
 

I have seen all sorts of threads over the years relating to 'which oil should I use ?'

No one can agree it seems and everyone has their own favourite.

When someone says I recommend '...... brand', on what are they basing their recommendation ?

As an example, as enthusiasts we probably change our oil more frequently than 'Joe Public'

If this is the case, we can't say that we recommend an oil because it 'lasts longer', even an average oil should be fine for the mileage we do between oil changes ?

Surely any recommendation has to be subjective ?

Unless we take two brand new cars, dismantle the engines and measure every component, refill them with our chosen oils, run them on a rolling road using identical parameters for a significant number of miles and then dismantle them again and measure the wear and tear, how can we ever truly know how well an oil performs ?

A biochemist may be able to analyse the composition of different oils and comment on their properties but this might not translate into 'real world' benefits ?

Subaru can't even give consistent advice !

They recommend 10-40 semi synthetic for the classic up to 2000 and 5-30 synthetic from 2000 on, as far as I know there were no major changes to engine internals from the last of the classics to the first 'New Age' models so why the different oil requirements ?

I used Millers 10-60 in my bugeye last year, not long after the bottom end failed, was this due to my choice of oil ?

Who knows !

I could have put some 'Tesco Value' in and the same thing might have happened or it might have been running still ?

I know this debate could run and run but I am genuinely interested in what criteria people are using when they make a recommendation ?

Is it a case of 'I used XYZ oil for the last four oil changes and the car hasn't blown up so it must be good oil' ?

Or is the any more scientific explanation ?

Please discuss amongst yourselves !

95% of people on here recommend an oil SOLELY because they've used it a couple of times and their engine hasn't blown up.

/thread

its not just because it hasnt blown up.. but the subaru specialists/engine builders such as harvey or api.. recommend these oils too and they've seen a lot of healthy and unhealthy engines..

Er, yes they're the 5% lol

It's more than just oil, it's liquid engineering!

Oil is like most things, you get what you pay for

The cumulative damage done at each oil change will eventually lead to a failure.

Most of "us" un-plug the crank sensor and spin the motor up to get some pressure before starting. I have an oil cooler, so have to pre-fill that as well before hand.

I use a 10W60 (Millers CFS) due to my cars mileage and track use. With a 5W30 it sounded like it was very tired, the thicker oil has quietened it down and it will last till the forged lump goes in, eventually.

All IMHO.

dunx

P.S. Obviously in a perfect world the thinest oil that is capable of doing the job will release the greatest power/best fuel consumption, and save the planet.

If anyone is running a stock car with no mods and servicing at the proper intervals, the stuff Subaru (and the likes of PSL) recommend will probably do the job.

But with upgraded power it makes sense to run better quality oil for the small difference in price. Lets face it that difference in price is less than half a tank of fuel FFS. We all take pride in our cars and want the best for them, so I choose to pay extra and run Mobile 1 15/50 in mine.

Anders

Whatever Subaru recommends. :thumb:

Or alternatively you pay a % for the brand name !

Im sure a % is because of the name but the quality is still better and offers better protection.

Subaru recommend oil for the standard power and general road usage. not modified and pushed around a hot track/drag strip

£40 for a decent oil is a small price to pay. i bet most people spend more on car shampoo/wax :lol1:

I have always used the best available quality oil in the 25 years I have been running cars.
The only exception was a Cortina Crusader I had as a mileage car with 100k on it.I ran that on cheap 20/50, changed it every 3k.
In the 80s and 90s I ran Golf GTIs, 328i, Saxo VTS, Cossies and used Mobil 1 in them all.
I ran my T5 on Duckhams QXR,changed it every 3k tops.
Ran my first 2 Imprezas on 10/40 Millers or similar.
Current Impreza run on 10/40 Millers for first 25k, then changed to 10/60.
Oil consumption is now zero, previously all my Imprezas have used around a litre between 6 monthly oil changes.
Any oil within the manufacturers recommended viscosity and blend, changed at the recommended intervals will be an unlikely cause of terminal failure of the engine.
A better quality oil may well prolong its life and provide additional benefits , such as reduced oil consumption.
Changing the correct viscosity and blend of oil regularly is more important in most standard, mildly modified cars.
I recommend 10/60 Millers as since I have used it in my remapped /decatted WRX, its oil consumption has improved.
Great question by the OP too....

This is what I mean !

What persuaded you to use 15-50 ?

This is way outside the parameters that Subaru recommend, even for the STi.

Is it because you have a sound technical argument to back up your choice or is it a case of Mobil 1 + more expensive = better oil ?

Please don't think that I am having a pop at you or your choice of oil, I actually used the Mobil 1 15/50 for the most recent oil change myself !

My reasons ?

I could not find anyone with a fully synthetic 10-40 in stock at very short notice, wondered if the 10-60 Millers had contributed in any way to the bottom end failure and did not want to use a 5-30 or 0-30 grade (my personal opinion ? too thin on a car with multi '000's of miles).

Does anyone produce a very high quality (scientifically proven not just expensive !) synthetic oil in the grade that Subaru recommend ?

Do their recommendations take into account wear / mileage on the engine ?

I presume they are basing their guidelines on 'as new' parameters ?

Going back to my point about the Millers 10-60, is it even vaguely possible that a thicker oil makes the oil pump work harder and possibly causes it to malfunction or fail ?

"I recommend 10/60 Millers as since I have used it in my remapped /decatted WRX, its oil consumption has improved"

Could that be because the oil is now so thick it can't get up the sides of the pistons and rings?

Is that a good thing?




:wonder:

No the failure is due to repeated damage at the oil changes, where the pump sucks fresh air for several seconds, the wiser on here will explain that a Scooby motor has relatively small bearing surfaces compared to non-flat-four designs.

The oil pump doesn't "know" how thick the oil is, unless down below 0 degrees C, it's increased viscosity is unlikely to have much effect. I've seen 125 degrees oil temp on track using Millers CFS 10W60, and the engine is still o.k., any problems mine has are down to age and mileage, Oh and the FMIC hose blowing off at flat-chat.

dunx

The oil pump does not know how thick the oil is but is does know the pressure. If the pressure is too high ('cos the oil is too thick?) then it dumps the oil back to sump. You still have high pressure but little flow to the vital bits....




:wonder:

Motul 300v competition 15W50..

Having ran my own engines for several 100,000miles and stripped and checked them and along with talking to a large number of owners.. I bought one subaru with 76k miles and that same engine untouched did over 200k miles, to one currently at 604bhp and done 13,000miles.

Simon

I go to the local push bike/car shop and choose the cheapest oil I can find and skick it in, thrash the pants off it for 6000 miles and then repeat process - seems to have worked fine for the last 5 years :)

snap, but I use the local Vauxhall 10W40 semi for the last 60,000 miles at 5000 mile intervals.

Just cleared 152,000 miles, with spare engine in the garage waiting for the death rattle.

I do do the prefill filter and disconnect crank sensor thing tho. Prefilling the filter makes sense and the crank sensor can't hurt, like crossing your fingers LOL




:thumb:

When I first bought mine in 2004 I never owned a Scooby before, I never owned a high performance car before, so oil choice was something I never looked at before.

After the 1000 miles running in, I asked what oil and they gave me a 1 litre of 5/30 shell fully synthetic and thought nothing of it, they should no best.

For the first couple of months I was getting used to the new car and the power but as soon as I started pushing hard down country lanes the oil pressure on the Defi's was very low when the oil was hot after I parked up on tick over, sometimes triggering the low oil pressure alarm on the Defi's (although not on the dash).

So I did some research and from the next service I supplied my own Mobile 1 15/50 oil and never looked back since. Tbh I think Prodrive should have specified better oil as part of the performance pack, after all the power was up 56bhp over a stock STI.

Anders

Halfords 5W/50 Fully Synthetic Track Day Oil 5L
K&N Performance Gold oil filter
Change every 5000.
No problems
Too much is read on oil viscosity etc,and you would be surprised at how crap the leading brands are.
Fit magnetic sump plugs on engine,box,diff and stick to the 5000 change:thumb:

I have owned my scooby for just over 2 years now. I never knew what oil i should use, checked the maunal and went for the Millers 10w40 CFS. Used for 2 oil changes and going to order again (I think?) I also pre-fill the filter (OE Subaru) but i have never taken the crank sensor off.
My car is only slighty moddied, decat sport exhaust and k&n stage 1 clutch and lighten flywheel.
I did own a 1.1 fiesta a long time ago used cheap oil and trashed it about and oil rings went.
After that I used GTX magnitec in a Modeo and GTX in an E30.

A guy at work changed his oil on a desil 306 every 5000 miles and it just kept going.

If i had the money i would change the oil every 6000 miles but it has been more like once a year (about 10000 miles).

Every one has there own opinion on this subject, but as said before it depends on how you drive, the mods on car, and if its track or road use.

There's my 2 pence worth.

Don't let Pete Lewis hear you saying that LOL




:thumb:

Castrol Edge 10-60
 

Hi,
Another vote for 10-60. Did a fair amount of research on here first mind. Always used on my 94 WRX from 45k up to 145k, so 100k proven miles. I believe it is worth paying more for the 'known' brands, but you can still save money. I'm an engineer, so a quick ring around our oil suppliers soon found a dealer who did Castrol, and a good discount was had. I always had to buy two cans, cos they are only 4 ltrs, but could get 3 for the price of 2 going through the 'supplier'. This made the fully synthetic oil better value than going through cheaper brands.

Having said that, it is quite feasable that someone using sub-standard oils, keeping them topped up, but not changing as regularly, COULD end up with a better engine than a guy who pays top dollor for his oil, changes every 3 thousand miles, but doesn't do it right. Oil changes not done properly can be downright damaging.

At the end of the day, oil is important obviously, but is no cure for an unsympathetic right foot, not warming up the car first, or prolonged high speed runs.

Mart

My local motor factor has just started stocking the Millers 10/40 so bought 5 litres for £36.

Seemed like a decent compromise and good value as well ?

I prefer to run millers 10w50 as the car is extensively modified

Banny

Maybe this thread should have two parts - recommending a grade of oil and recommending a brand.

Well actually its not ;) subaru recommend oils with a 5, 10, 15 and 20 cold weight (new age) and a 30, 40 and 50 hot weight, they dont recommend a 60 weight though, and STI's own oil is actually Motul 300v 15w50 ;)

Tony:)

I would be a little worried if your scoob used oil before changing it to such a thick oil as a 60 weight, none of the 4 scoobs I have owned used oil, 2 of those from new, 3 ran on semi synthetic, 2 that I owned from new ran on 10w40 semi synth for 5-6k before changing to fully synthetic, latest 2 scoobs both run 5w40 shell helix ultra, no oil useage at all ;) even after hard driving!

Tony:)

Aren't those recommendations for different temperature ranges across the world ?

I seem to remember some 'graph' type diagrams in the handbook showing which oil grades for ambient temparatures 'from' and 'to', I suppose Scooby owners in Siberia need oil too ?