Motorcycle Oil In Car Engines ?

[Tham]

Can one actually use motorcycle 4-stroke oil in a car's engine ?

 

http://www.castrol.com/castrol/sectiongene...ntentId=7018616

 

http://www.castrol.com/castrol/sectiongene...ntentId=7040925

 

 

I've noted that the API rating is at least SE for most 4T motorcyle

oils, so I was thinking it would be up to specs for car engines.

The grade is just about right, SAE 20W-40.

 

The car engine oils in Malaysia oils in 1 liter cans are more

commonly SAE 40. I was thinking that if I needed to top up

(my old engine is consuming quite a bit of oil), it would be

more cost-effective to get a SAE 20W-40 motorcyle oil, since

these cost about the same for a liter as SAE 40 car oils -

about M$10.

 

They also have the usual additives anyway - antioxidants,

dispersants, detergents.

 

One of my friends said he had topped up with 4T oils and

didn't find any problems.

 

I drive a 1981 Corolla KE70, 4K engine.

[styler]

why not just buy 4L of car oil for a few more dollars and use that?

 

motorbike oils are the same i believe but with gearbox crush additives and maybe wet clutch additives?

 

ie - don't use car oil in a wet clutch (common) motorbike... but as for using motorbike oil in cars thats a new one!

[Tham]

4 liters of car oil would actually be cheaper

than four 1-liter cans of motorcycle 4T oil.

 

The basic 20W-50 car engine oil, Repco, costs M$30

here for a four liter can. It sells at M$10 for a 1-liter can.

 

Four 1-liter cans of basic Castrol 4T motorcycle oil,

20W-40, at M$10 a can = M$40. Perhaps the shop

might give me some discount if I bought 4 cans, though.

 

I was just thinking of trying out something new to see

how the engine performed, plus it's more convenient

to keep a 1-liter can of oil rather than a bulky 4-liters

in my boot !

[slapper]

The short answer is "for a 1981 KE70, yes".

So long as the viscosity is comparable, go for it. 20W-40 might be a little thin at operating temperature, so I wouldn't be using it all the time though .. just for top-ups here and there. If you're thinking of using Castrol 4T, I'm pretty sure it's 15W-50 which should be fine ... a trifle thin when cold though.

 

why not buy a 1 litre bottle of the bike oil then top it up as required from a 4 litre car oil? That way you ultimately only pay $30 for 4l but have the convenience of the 1 litre bottle :P I do exactly the same thing the other way around. On my motorbike, I carry a 1 litre Castrol GTX2 bottle filled with Castrol Activ 4T.

 

I must say that it's unusual you can buy a litre bottle of bike oil cheaper than a litre of car oil - here it's usually the other way around by quite a margin!

 

 

 

Motorbike oils usually have shear resistant viscosity polymers to resist the chopping action of the transmission. The advent of high revving small capacity engines in cars means these are turning up more often in car oils nowadays as well. In tests I've read (in a magazine) conducted at a university in the States, the current batch of car oils (last year) performed pretty much as well as the bike oils in maintaining their viscosity when used in a motorcycle.

 

Bikes usually share the engine oil with the clutch as well as the transmission, so they're also not friction modified as a rule. Friction modifiers can wreak havoc with the clutch plates.

 

Car oils stopped including a couple of "last resort" metal-on-metal lubricant components when catalytic converters came in - phosphoric compounds I think. These components weren't friendly to cat's and the requirements for cars to meet emission goals for 10 year old cars meant the cat still had to be intact. Motorcycles are only recently seeing the introduction of cat's and they're not yet subject to the same emission laws, so motorcycle oils often still carry these same compounds. You don't need to worry about the longevity of your catalytic converter in a 1981 KE70 though!

 

cheers,

Slapper

[slapper]

ahh ... just followed your links.

 

Looks like Castrol 4T is available in 10W-40 as well as 20W-50.

I wouldn't run a 28 year old car on 10W-40 alone ... too thin. For a top-up here and there it's probably fine though.

The 20W-50 would be a much better option.

 

If you can't get the 20W-50, do the bottle top-up trick to put 20W-50 car oil in the bottle.

 

cheers

[Tham]

Thanks very much for your good information, Slapper.

 

The reason I preferred SAE 20W-40 oil is that it is a bit thinner

than 20W-50. The latter oil is somewhat thick, and it tends to

make my old engine accelerate very sluggishly. There are no

car engine oils here at 20W-40 grade, but plenty of 15W-40

and 15W-50 oils. 15W-40 here costs M$38 for the cheapest

brand ("76", an American oil, 1 US gallon or 3.785 litres).

Pennzoil 15W-50, if I buy it at their factory here, costs M$46

for 4 litres.

 

The second Castrol link I gave you is actually a US website, and

they don't have 20W-50 for the basic 4T oil here in Malaysia.

Activ 4T has it, but I checked at the shop and it costs M$15

a litre. There's only one cheaper 20W-50 oil here, the local

"Modenas" brand, at M$12 a liter.

 

I then walked into another motorcycle shop to check more

on the prices. The owner seemed quite knowledgeable, and

he told me that while ordinary motorcycle 4T oils could be

used in a car engine, it would run sluggish, as these oils

were designed to be used on a system with wet clutches,

and thus were heavier or less slippery than car oils.

 

I believe he meant that, as you pointed out, they don't

have friction modifiers. He said that oils for scooters

were the exception, since scooters had similar systems

with cars - they had separate transmissions and clutches.

Thus their oils were similar too, and could be used

without any problems on car engines.

 

However, scooter oils are more expensive, with the

cheapest standard oil here at around M$18 a litre.

 

For quite a few years, I was using Pennzoil HDX 30,

SAE 30 (monograde), meant for diesels, but rated at

CD/SF, so petrol engines could use them too. Good

acceleration, but thins out at higher temperatures.

You can hear my timing chain rattling away on a hot

day. You can buy it at the Pennzoil factory here at

M$33 for 4 litres currently, was M$39 last year

(several years back, when I first started using it,

was M$19 ! )

 

I still have an unused 1 litre bottle of this HDX 30,

so I'll follow your advice and use it to fill with 20W-50

for topping up, when it's used up. This cost me M$8

two years ago, I remember.