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Is alight to use regular oil in my bike. Its a older bike 85 Kawasaki Zn 700. Regular car engine oils or should u absolutely use like a oil that says wet clutch protection

Do not use regular car oil. It will ruin the clutch.

There are MANY different oils out there that meet the JASO-MA standard and have that designation printed on the container. Some are very inexpensive - they don't cost any more than regular car oil. So why ruin a clutch and go through the expense and hassle of replacing the friction plates when you can simply use the correct oil for your machine? Ed

650ed wrote: Do not use regular car oil. It will ruin the clutch.

There are MANY different oils out there that meet the JASO-MA standard and have that designation printed on the container. Some are very inexpensive - they don't cost any more than regular car oil. So why ruin a clutch and go through the expense and hassle of replacing the friction plates when you can simply use the correct oil for your machine? Ed

Ed is right
I use Shell Rotella diesel oil , as do a lot of members. Readily available at stores every where and cheap. Loaded with zinc as needed.
Lots of other choices on the market , but this oil works great
Dave

How does regular (conventional) car oil hurt the clutch?
I know many of the lighter weight oils have friction modifiers, but 10W-40 & higher shouldn't have the additives, so the friction modifier stuff shouldn't be an issue with an old KZ since Most regular oils don't have as much zinc-phosphate nowadays (if any), but I think that's more of a long term wear issue (except, supposedly, for vintage flat tappet engines & maybe some others). I'm probably overlooking something. hee. I normally use Shell Rotella or Chevron Delo 15W-40, but I did use Valvoline conventional oil one time last year & didn't have any problems.

PS: please don't suggest going to the bobistheoilguy site.

The original question asked was "Is alight to use regular oil in my bike."

Regular car oil includes a lot of different weights and quality oils - including to my knowledge every "energy conserving" oil that contains friction modifiers which have been proven to ruin wet clutches. So given the generic nature of the question I still believe the correct answer is "no" even though there may be some exceptions to the rule. I have seen folks on this and other sites use nearly every weight oil available including straight 30w oil that they had stored in their garage since the 1960's, so I am not particularly confident that the original poster would always use 10w-40, especially since he seems somewhat unsure as to what oil is appropriate.

A second issue, as you point out, is that automotive oils (unlike motorcycle oil and at least some diesel oils) contain less ZDDP than they did when our bikes were made. ZDDP was found to cause problems with catalytic converters, so its use was reduced or eliminated in various car oils. The lack of ZDDP has been reported to cause problems with solid tappet valve trains (like those on KZ engines), so that is another reason not to use car oil in a KZ engine on a regular basis.

Personally, I am not totally convinced that 10w-40 automotive oil will NOT cause problems with wet clutches. I bought my bike new and always used Castrol GTX 10w-40 car oil. About 1 - 2 years after the Castrol oil formula changed my clutch started slipping. It could be a coincidence for sure, but when Castrol removed or reduced the ZDDP in their formula they replaced it with something else to reduce the rate of wear in engines. Whether the something else was moly or some other additive I don't know, but it may have been the cause of my clutch slipping. I'm not suggesting that the clutch will fail immediately, but over time and miles there may be a gradual buildup of the new additive on the friction plates. The friction plates in my clutch had zero sign of burning, but they seemed to be impregnated with a substance that made them slip. In any case, replacing the slipping clutch caused me to read up on oils, and that's when I learned of the JASO-MA standard. That was 9 years ago. I have been using Mobil-1 Racing 4t oil, which is JASO-MA compliant, since then and have experienced no clutch problems. Given my experience I would recommend that anyone with a KZ use oil that is JASO-MA compliant. It doesn't need to be Mobil-1 Racing 4T. As Street Fighter LTD pointed out many folks use Shell Rotella diesel oil (which is JASO-MA compliant) with great success. Ed

With semi-racing Barnett clutch springs, I ran straight Castrol GTX 10-40 and 20-50 for thirty years!!
I've NEVER had a clutch slippage issues. It has +37,000 miles on it.
It just does not slip at all... and I have had used bikes with loose plates and slippage.
I only started using carefully selected JASO-MA oils since the chatter about it on the NET a few years ago.

missionkz wrote: With semi-racing Barnett clutch springs, I ran straight Castrol GTX 10-40 and 20-50 for thirty years!!
I've NEVER had a clutch slippage issues. It has +37,000 miles on it.
It just does not slip at all... and I have had used bikes with loose plates and slippage.
I only started using carefully selected JASO-MA oils since the chatter about it on the NET a few years ago.

I used 20w50 Castrol GTX from day one with no problems ,Until one day after a oil change the bike just didn't feel right. My clutch issues were masked by heavy clutch springs and my Karata Glide Lock up device. . Talked to some folks in the business I trust and switched to proper motorcycle oils and then Rotella . I am not sure when Castrol switched formulas , but It was a deal breaker for me to continue using it
Dave

I was definatly unsure. Thanks for ALL the input. I know I'll get more then 1 answer and a couple different opinions and that's more important to me.

I used to use auto oil in my bikes all the time and it never hurt my clutch. Since the advent of reduced zinc and phosphorus in auto oil in recent years I now use diesel oil. Doesn't matter which one. Rotella is certified for use with a wet clutch, but just because the other diesel oil's aren't, you can use them just the same. Diesel oil manufacturers don't sell much oil to motorcycle guys, so most makers don't want to spend the money to get the wet clutch certificate. Rotella, Delo, Motorcraft, Valvoline Fleet, I've used them all.

martin_csr wrote: How does regular (conventional) car oil hurt the clutch? Seriously,
I know many of the lighter weight oils have friction modifiers, but those are the wrong weight for motorcycles, so the friction modifier stuff shouldn't be an issue with an old KZ since 10W-40 & higher shouldn't have the additives.

But you don't know if they do since the oil makers are not putting any info on the label about anything. I don't trust them at all. It is true that 10-40 and 20-50 don't usually have friction modifiers and don't have the "energy efficient" label. I'm not sure that I would trust that anymore unless the MA label is there.

And as pointed out, you need to add ZDDP to get up to proper levels for this type of engine.

Hey Bounty Hunter when you say you need to add zddp are you talking a specific additive or maybe STP ? Been using 10/40 Valvoline bike oil lately and will probaly stick with it.

If it's motorcycle oil the zddp content should be fine. It was reduced/eliminated in car oil because it damaged catalytic converters, but I don't think they messed with motorcycle oil. Ed