Can I put Oil for a Car Into My Motorcycle?

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Many motorcycle drivers are given conflicting recommendations about what type of oil to use in their vehicles. Numerous motorcycle manufacturers heavily promote the use of specially formulated motorcycle oils, claiming that these are better for the life of the motorcycle and will not wear down as quickly. In fact, it is perfectly safe to use oil formulated for automobiles in motorcycles, as long as the oil is of an appropriate viscosity and the motorcycle is kept well maintained, as all motor vehicles should be.

In most cases, it is recommended that motorcycle drivers use synthetic oils in their vehicles. Synthetic oil is more expensive than natural oil, but will stand up to wear and tear better, and tends to keep desired properties longer. Most oil companies are making affordable synthetic oils available and it is well worth the minimal extra investment to be assured a longer performing oil. Synthetic all purpose oil is still less costly than oil designed specifically for motorcycles.

All oil provides a rating which indicates the viscosity of the oil. The lower the rating, the lighter the oil is, meaning that it flows very easily. This is not an issue at low temperatures, but as the engine heats up, the oil will rapidly begin to degrade, and get very hot. As a result, drivers want an oil of high viscosity to ensure smooth running of the engine at high temperatures. Many oils come with a combined rating such as 20W-50, indicating that at low temperatures the oil flows smoothly and as the engine heats, the oil retains viscosity. Single grade oil is available, but multigrade is recommended.

The claim made by many manufacturers of specially formulated motorcycle oil is that oil designed for cars may actually damage the engine of a motorcycle. This is simply not true. While some oil designed for automotive use is not optimal in motorcycles, most oil is easily interchangeable, although motorcycles are more demanding on oil than cars are. Motorcycles still operate along the same internal combustion principles as cars do, after all.

In scientific testing, it has been determined that motorcycles will break down oil more quickly than cars, with the results being the same for both types of oil. Oil breaks down as repeated circulation shortens the polymers in the oil, causing the viscosity to be lowered. In addition, increased oxidation and repeatedly running too hot will cause oil to break down and become less effective. Testing also determined that synthetic oils are not as subject to break down as natural oils, and are therefore a better choice for drivers.

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11
Its all confusing Can you use auto synthetic in a motorcycle or not?
- anon49788
10
I find it quite interesting to see that you recommend automotive oil. It makes me wonder if you are aware that the api changed the performance standards in '96 which causes for lower zinc and phosphorus which protects the wear of mc also that they have friction modifiers which can cause wet clutch slippage. this article certainly is not by a mechanic.
- anon49347
9
Do the research on oil and you will see that synthetic is far superior to conventional oil in every way. It's all I use in my motorcycles and cars and I tend to use all the available horsepower. No wet clutch problems, ever. There is nothing wrong with modern regular oil and it will work well in all vehicles, *but*, synthetic will last longer, create less sludge, stand up to heat better and reduce wear. It's just better.--John
- anon35597
8
Kilroy, I do not accept your "facts" because in 22 yrs. of riding all my bikes have had wet clutches and car oil was always used, typically Mobil 1 and Rotella. Even my dirt bikes which take significant clutch abuse have never slipped. Enough with consumers paying rip-off prices for "motorcycle" oil.
- Lammy1000
7
If you use semi synthetic oil, might as well send your extra expense to the relief center for the Rich People Foundation. All you are doing is throwing your money away. Amzoil is a great product as Mobil1. Shell Rotella Synthetic is great too. At one time or another, I have used these three brands and have never had any trouble with my bikes 38 yrs. to be exact. All my cars and truck run on Mobil 1.. Why?? Because, I can run to Wal Mart and buy it there... Amzoil is purchased through a dealer or distributor... Shell is much cheaper but it's still great oil..
- fvasqu01
6
Automotive oils have friction modifiers that can cause wet clutches in motorcycle engines to burn up quickly. I have changed a few hundred because of unknowing owners. At a cost of $300 to $1100 per clutch, it isn't cheap.

So save yourself the money and quit paying a mechanic. Motorcycle oil isn't much more than auto oils, plus most motorcycles hold less oil than cars. Don't for get to change the filter.

- anon26352
5
I'd listen to Kilroy. The one thing that most people don't notice is that even though cars and motorcycles share the same engine design, there is a fundamental difference. Motorcycles share their oil with the transmission while cars have separate sumps for the transmission. Adding friction modifiers to your engine may sound fine but it has an adverse affect on your clutch. It's just the place where you really don't want any slip.

Also I've used Motul Synthetic in my V-Strom and rode it across Canada and back. The Synthetic is made for motorcycles and it ran fine. It even seemed to have cured the notchy transmissions that Suzuki's seem to have.

- anon19511
4
So does this still apply about car oils vs. motorcylce oils if your bike says 4 stroke engine?
- anon14711
3
I use synthetic auto Oils in many bikes for years.

Synthetic is the way to go!

Most bikes only say 10w40.

Just worry with that.

And many of my friends do the same.

I even remember a website where a guy said he used mobile one on a cbr900 for 200.000 miles with no problems whatsoever!

Wet clutches ... what's next the buggy man?

- anon6275
2
Kilroy -- you state - "it is not recomended to use full synthetics in motorcycles semi-synthetics maybe but not full." I question this simply because if you go to a circuit, you will easily see all the racers using the full synthetic oils. Being 52yrs old now and racing street and dirt along with owning my fair share of street motorcycles, I will say using Rotella oils are the best overall.
- anon1287
1
Ok so something I would like to know where did you get your info consering the compatablity of car oils vs. motorcycle oils. Also are you refering to motorcycles with wet clutches, or motorcycles with separate transmisions? If its the former you most likely have damned people to an early clutch replacment, as the blended oils that are used in cars will make them slip. also it is not recomended to use full synthetics in motorcycles semi-synthetics maybe but not full. Now if it was not important to run a specific oil type in a bike why then do many of todays oil brands offer motorcycle oils? with over 15 years of service work on bikes I have seen first hand what can come from using the wrong oils in a bike. There are many oils out there you can run but please stick with one that states its blended for motorcycles.

The oil companies and there salesmen will always say its safe to run there brand when asked, but when it comes to damage due to running their car oil in a motorcycle they are quick to piont out that its not designed to run in a motorcycle!

- Kilroy

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Written by S.E. Smith
Last Modified: 22 October 2009

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