Synthetic Myths

[oilman]

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

[sotal]

Just a quick question re: synth oils and myths whilst you are on the subject, it's one I've read lots of conflicting advice about.

Statement: You shouldn't use Synthetic Oils with a wet clutch setup

Is it a Myth or not?? The accepted answer that seems to be floating about is not to use synthetic oil when the engine is new, but once it's done 15,000 miles you are ok to switch from semi-synth to fully synth - I can't quite understand what difference it makes once the engine has done 15k though???

This is in respect of Motorbike Engines

[Jamesb4uk]

oilman are you the same chap on 300zx.co.uk?

J

[oilman]

Just a quick question re: synth oils and myths whilst you are on the subject, it's one I've read lots of conflicting advice about.

Statement: You shouldn't use Synthetic Oils with a wet clutch setup

Is it a Myth or not?? The accepted answer that seems to be floating about is not to use synthetic oil when the engine is new, but once it's done 15,000 miles you are ok to switch from semi-synth to fully synth - I can't quite understand what difference it makes once the engine has done 15k though???

This is in respect of Motorbike Engines

←

Most quality bike oils are synthetic.

No you should run in on mineral or semi-synthetic as fully synthetic prolongs the bedding-in process.

Cheers

Simon

[oilman]

oilman are you the same chap on 300zx.co.uk?

J

←

Yep, that's me.

Cheers

Simon

[Gnome]

Have only ever used Semi-synthetic on my Bandit engine, as using fully synthetic has led to clutch-slip problems for alot of Bandit motorcycle owners.

Other bikes don't seem to suffer as much as a problem compared to the old oil-cooled Suzook engines.

[sotal]

Have only ever used Semi-synthetic on my Bandit engine, as using fully synthetic has led to clutch-slip problems for alot of Bandit motorcycle owners.

Other bikes don't seem to suffer as much as a problem compared to the old oil-cooled Suzook engines.

←

Yeah I've only used semi-synth in my yzf600r but then I'm only at 7k so it's not bedded in enough yet I guess. The manual does state not to use fully synth as it will cause clutch slip but most riders on the forums prefer fully synthetic and make the change to it as quickly as possible

[Gnome]

Whats the advantage of fully-syn, over semi?

The Bandits on 32K miles now, and it's only been fed on semi.

[oilman]

Shear stability (stay in grade longer) and better all round protection.

Cheers

Simon