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SYNTHETIC MYTHS
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Old 30 Nov 2005, 12:59 PM   #1 (permalink)
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SYNTHETIC MYTHS

I read so much stuff on the internet about Synthetic Oils that is simply not true so I felt it was time to tell the truth rather than accept the myth.

So in future when you see someone state any of these, please do me a favour and point them at this thread!

Synthetic motor oils damage seals:

Complete Nonsense! Any oil seals made after 1975 or thereabouts will be entirely compatible with any type of synthetic engine oil. (The same goes for synthetic gear oils and transmission oil seals.) It must be understood that everything associated with lubrication is thoroughly tested. The major oil manufacturers do not make oils that attack seals; seal manufacturers ensure that their products function correctly with modern lubricants.

Synthetic oils are too thin:

It is true that the best synthetic blends can be low viscosity (0w-20 for example), but they do not have to be! It is also true that the latest engines are designed to run on thin oil, which improves power output and fuel consumption. Even so, thicker synthetic based grades (10w-50, 15w-50, 20w-50etc) are available for air-cooled motors, older engines, or severe high temperature conditions. These grades can also benefit rebuilt classic engines dating back to the 1940s.

Synthetics mean higher oil usage:

The complete opposite of the truth. Oil consumption in well-maintained modern engines is mainly down to the oil evaporating at high temperatures. Synthetic base oils (specially the PAO and ester types) are very resistant to evaporation loss even in low viscosity blends, so oil consumption is minimised. Obviously, engines with worn valve guides, defective seals and worn piston rings will use oil regardless, so there is no point in using expensive synthetics as an ‘old banger lube’.

Synthetic oils are not compatible with other oils:

All engine oils intended for normal road use in recent 4-stroke engines are compatible with one another, regardless of the base make-up. (mineral, PAO/ester/hydrocracked synthetic, and semi-synthetic.) There is no need to flush or strip down an engine when changing from one type to another. (…but be careful with the exception: castor oil based racing oils.)

Synthetic oils produce sludge:

Well honestly, this is just totally daft. All synthetic bases are more resistant to oxidation than mineral oil, and sludge is largely due to oxidation. In any case, all motor oils intended for road use meet the higher API specs such as SH, SJ, SL and diesel equivalents. One of the main reasons for introducing the API specs back in the 1950s was to deal with oil sludge problems. All high-spec oils run very clean, especially synthetics.

Synthetic oils cannot be used with catalytic converters:

‘Cats’ will perform more efficiently and last longer if synthetic based engine oil is used. Their lower volatility (see 3 above) means that less oil reaches the combustion chambers via crankcase ventilation, so there are less harmful ash residues from burnt oil to de-activate the catalyst matrix.

Synthetic oils can void warranties:

People who make statements such as this never define the type of synthetic, thus revealing their ignorance. Provided that an oil meets or exceeds the API and viscosity ranges specified in the handbook, the warranty will not be affected. (By law, OEMs cannot insist that a particular brand of oil must be used to maintain warranty.)

Synthetic oils will last forever:

The better synthetic blends will certainly last longer*, especially in high performance or high annual mileage situations, but ‘forever’ is not on, simply because contaminants such as soot, and acid gasses from traces of sulphur in the fuel degrade the oil.
(*Provided that a very shear resistant VI improver polymer is used in the oil formulation to keep the viscosity up to spec. This point is often forgotten.

Synthetic oils are too expensive:

True, for older vehicles that use a lot of oil or are almost ready for the scrap yard. For cars that are worth maintaining, the right types of synthetic oil are a cost-effective way of retaining ‘as new’ performance, low fuel consumption, and reducing maintenance costs. (See 6 above, for example. ‘Cats’ aren’t cheap!)

Cheers
Simon
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Old 30 Nov 2005, 01:25 PM   #2 (permalink)
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Simon
Thanks for yet another informative/educational post about Oil
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Old 30 Nov 2005, 02:16 PM   #3 (permalink)
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Pete,

Looks like you're the only one that appreciates them though

Cheers
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Old 30 Nov 2005, 03:51 PM   #4 (permalink)
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Simon it is getting the views m8, I just think some are a bit shy :wink:
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Old 30 Nov 2005, 05:23 PM   #5 (permalink)
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i read them but you normally cover all of it so no need to ask
what grade would you say for subaru,s ?and any manufacturer?
engine ?
diff ?
gbox?
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Old 30 Nov 2005, 05:33 PM   #6 (permalink)
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>|<>QBB&l:
Quote:
Originally Posted by Sirus
i read them but you normally cover all of it so no need to ask
what grade would you say for subaru,s ?and any manufacturer?
engine ?
diff ?
gbox?
Your sig says 99.

10w-50 - engine
75w-90 - gearbox and diff

Good makes, Silkolene, Motul, Fuchs.

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Simon
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Old 30 Nov 2005, 05:38 PM   #7 (permalink)
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sorry should have mentioned year
thanks on the info
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Old 30 Nov 2005, 06:59 PM   #8 (permalink)
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:? :? my oil pressure on mine when i got it mapped was a little low when it was really warm & when i found out the dealer had put either 10 or 15 / 40 semi in i was told to try 10/40 fully in this weather then when it gets warmer weather go for 15/50 or 10/60 even fully ........... doews this sound about right simon ................... ???????????

cheers ............ :wink: :wink:
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Old 30 Nov 2005, 07:59 PM   #9 (permalink)
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Which year is the car?

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Old 30 Nov 2005, 08:05 PM   #10 (permalink)
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>|<>QBB&l:
Quote:
Originally Posted by oilman
Which year is the car?

Cheers
Simon
It's a 99 T plate mate ............. :wink:
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Old 30 Nov 2005, 11:09 PM   #11 (permalink)
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Personally I would use Silkolene PRO S 10w-50 all year round.

Cheers
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Old 01 Dec 2005, 06:45 PM   #12 (permalink)
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>|<>QBB&l:
Quote:
Originally Posted by oilman
Personally I would use Silkolene PRO S 10w-50 all year round.

Cheers
Simon
ok simon cheers for reply .....................
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Old 07 Dec 2005, 06:30 PM   #13 (permalink)
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Excellent post, Simon.

Although I tend to disagree with recommending a 10W50 for a 99 car.

In line with you post, I would recommend a 5w40 or 0W40 for any car. True, it's more expensive. But hey, what is a few GBP more to protect your engine well ?

W50 I noticed works well for someone who does quite a bit of track work, but for normal daily use, especially in winter, I would use W40 in the UK and W30 if living more North on the planet.

I personally use 5W30. The 10W40 these tw@ts at the dealership put in my car last year didn't quite do what it said on the box (i.e. lubricate) last winter :evil:
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Old 08 Dec 2005, 11:11 PM   #14 (permalink)
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hi all,just bought my first scooby and want to protect it well.it's a '95 wrx with 38,000 miles and is totally standard.what would anyone recomend for an oil given model and mileage.also just another bit of advice,the car as i mentioned is totally standard and was only imported in march this year along with all the certificates from BIMTA certifing the history and mileage.i haven't really give it a good hiding yet but i have noticed that occasionally when putting my foot down it will hiccup a bit borderlining on a missfire around 4500 rpm.could this be down to the fact that the car has not been set up to run properly in this climate or is there another reason behind this.cheers buddies.lee..
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Old 09 Dec 2005, 10:34 AM   #15 (permalink)
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You've 2 options really.

Price = Semi-synthetic 10w-40
Quality = Fully synthetic 5w-40

Cheers
Simon
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