Oil Consumption Quandary on a 1999 Honda CBR600F4

September 1999

I picked up my CBR600F4 this past March (1999) and I have about 5,500 miles on it. This is my third CBR600. 1st was a 1993 CBR600F2 (picked it up used in 1995), 2nd was a 1997 CBR600F3 (bought new) and now the 1999 CBR600F4 (also bought new).

I usually do my own maintenance on my cars and motorcycles and I always use the authorized service manual for each vehicle.  I'm not a professional mechanic but I do have enough experience to do more than just change the oil, filter, spark plugs, and brake pads.  I also use that torque wrench in my tool box.

I've been having a problem with my F4 consuming oil.  I keep having to add 1/2 to 1 quart of oil after every 400 to 800 miles. There are no leaks anywhere on the bike that I can tell.  According to the guys I ride with, there is no smoke coming from my exhaust, even under hard acceleration or deceleration.  The other day I pulled off both lower body panels and the gas tank and opened up the air box.  When I looked into the carburetors, all of the intake valves (8) had black deposits on them. The nose, tip and electrode of all the plugs are covered with black deposits. I replaced all of the plugs, especially since it was such a pain to get them out.

None of my previous CBR600's consumed oil.  Let's just say that all three bikes were ridden using their full RPM rage. So I didn't baby them. But I didn't abuse them either.  Everyone I spoke to, except the dealer and Honda Customer Service (HCS), agrees that this behavior is not normal, especially for a new bike. The owner of the dealership I purchased the CBR600F4 from said that 1 qt. per 1,000 miles is normal. But, that's not my experience.

In July, I switched from Honda GN4 10W-40 to Honda GN4 20W50 because the weather had been very hot. The GN4 20W50 did not make a difference.

HCS suggested that I switch back to 10W40 (thinner) oil and ride the bike hard, because the rings may not be properly seated yet. HCS also suggested that I could pay to get a compression and leak down test done on the CBR600F4 to see if the engine is within spec.

And yes, the oil is checked with the bike on level ground in the vertical position, not on the side stand, per the owner's manual.  Also I make sure to not overfill.

All CBR600F4 owners:

Please check your oil level on a regular basis so that we can determine if the problem that I am having is something that other CBR600F4 owners should be concerned about.

When you check the oil level, check it when the engine is cold and after it was warmed up to see how much difference there is between the cold and warm oil levels. 

Note: If you are planning on using Semi-synthetic or synthetic oil on the CBR600F4, make sure that you find out what additives are in it.  Honda does not recommend using their HP4 Semi-synthetic in the CBR600F4.  The owner’s manual states the following on page 80:

"Do not use oils with graphite or molybdenum additives. They may adversely affect clutch operation."

I've been speaking to several knowledgeable people trying to get as much information as I can on this problem, especially since none of the usual suspects are present: puddle of oil on the floor, blue smoke coming from the exhaust, etc.

Q: What would cause all four spark plugs and all the intake valves to become fouled with oil?
Q: Should I be concerned about engine being damaged if I continue to ride it this way, as long as I make sure to add oil when necessary?
Q: How much should a compression and leak down test cost?
Q: What else can I do in an attempt to find out what the problem is?

Update: April 2000

Another dealer did a leak down and compression test on my CBR600F4. The service manager says that both sets of numbers are just about perfect. All were at or above the Honda recommended specifications. Here are the results:

 

1

2

3

4

Compression Test

217 psi

211 psi

218 psi

226 psi

Leak down Test

-1%

-1%

-1%

-1%

 

Update: June 2002

I'm glad to report that there isn't a problem with my CBR600F4's engine. It no longer consumes oil after I switched to Mobil 1 MX4T 10W-40 synthetic oil.  It appears that the Honda GN4 oil I was using was degrading too soon, compared to the Mobil 1 MX4T. I can now go the full period of 3 to 5,000 miles before changing the oil and filter without the need to add oil.

Using any good synthetic oil, after the break-in period recommended by Honda, should alleviate the problem. Just make sure that you:

"Do not use oils with graphite or molybdenum additives. They may adversely affect clutch operation."

 

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