Engine Oil Choices for a Z1

First a bit of background.  I just completed replacing the head gasket and most of the cover and oil pan gaskets to stop the leaks I've been having on my 73 Z1.  As long as the oil pan gasket was off, it was a good time to check the oil pump.  The screen was a bit clogged with what I would think is a bit of clutch material, not so unusual, so remove the oil pump, disassemble, clean, inspect and put back together.  Upon opening the pump, the gasket came apart in several pieces, some of which had to be scraped to remove, so consequently I needed a new gasket.  The gears and clearances seemed to be in good shape and within spec, at least for side clearance.  I did not measure the end clearance since I didn't have any Plastigage handy.  When the new standard sized gasket arrived, it seemed a bit thicker than the original, but then, the original had been compressed, so in went the new gasket and the oil pump was reinstalled.  This engine has never had a problem with low oil pressure but now I'm seeing the oil light come on at anything below 1500 rpm when hot.  Does anyone know what the switching pressure is for the oil pressure switch?

So, here's the question:  I filled the engine with Shell Advance AX5 20W-50 Motorcycle Oil( rb.gy/p1sgim ), could this be the problem?  It did seem a bit runny for a 20-50.  I'm thinking perhaps I should switch to a Kawasaki brand oil, but which one?  The K-Tech SAE 20W-50 4-Cycle Engine Oil( rb.gy/eej8ji ) touts "Protects against excessive viscosity decrease at high temperatures", which seems to be my exact problem at the moment.  Or would the KPO Conventional 4-Stroke Engine Oil( rb.gy/efv20u ) or the 4-Stroke Motorcycle Engine Oil 20W50( rb.gy/b4izgu ) be better or maybe even worse.  I'm thinking that any one of these should be an improvement but would like to hear of any knowledge or experiences to determine which would be the best choice.

This is my first step in diagnosing this problem, which is the easiest thing to do before tearing back into the engine.  Pressure testing cold is about 2 psi at 3000 rpm, a bit on the low side, but is it the oil or the pump?  Now I wish I'd never opened up my working oil pump.    A clear case of "If it ain't broke . . ."

  

sdinse wrote:

First a bit of background.  I just completed replacing the head gasket and most of the cover and oil pan gaskets to stop the leaks I've been having on my 73 Z1.  As long as the oil pan gasket was off, it was a good time to check the oil pump.  The screen was a bit clogged with what I would think is a bit of clutch material, not so unusual, so remove the oil pump, disassemble, clean, inspect and put back together.  Upon opening the pump, the gasket came apart in several pieces, some of which had to be scraped to remove, so consequently I needed a new gasket.  The gears and clearances seemed to be in good shape and within spec, at least for side clearance.  I did not measure the end clearance since I didn't have any Plastigage handy.  When the new standard sized gasket arrived, it seemed a bit thicker than the original, but then, the original had been compressed, so in went the new gasket and the oil pump was reinstalled.  This engine has never had a problem with low oil pressure but now I'm seeing the oil light come on at anything below 1500 rpm when hot.  Does anyone know what the switching pressure is for the oil pressure switch?

So, here's the question:  I filled the engine with Shell Advance AX5 20W-50 Motorcycle Oil( rb.gy/p1sgim ), could this be the problem?  It did seem a bit runny for a 20-50.  I'm thinking perhaps I should switch to a Kawasaki brand oil, but which one?  The K-Tech SAE 20W-50 4-Cycle Engine Oil( rb.gy/eej8ji ) touts "Protects against excessive viscosity decrease at high temperatures", which seems to be my exact problem at the moment.  Or would the KPO Conventional 4-Stroke Engine Oil( rb.gy/efv20u ) or the 4-Stroke Motorcycle Engine Oil 20W50( rb.gy/b4izgu ) be better or maybe even worse.  I'm thinking that any one of these should be an improvement but would like to hear of any knowledge or experiences to determine which would be the best choice.

This is my first step in diagnosing this problem, which is the easiest thing to do before tearing back into the engine.  Pressure testing cold is about 2 psi at 3000 rpm, a bit on the low side, but is it the oil or the pump?  Now I wish I'd never opened up my working oil pump. 

  A clear case of "If it ain't broke . . ."

  

Whatever oil you use do not use fully synthetic.
Only mineral or semi synthetic.
Depending on your climate 10/40 or 20/50 is all that is required.
These engines are high volume - low pressure so around 3 psi is normal but if you have increased side clearance in the oil pump due to a thicker gasket etc this will reduce the pressure.

I’m a big fan of good ol’ Rotella T4 Dino oil. 

I use Rotilla also. I opened my pump in 2015 and sanded the side plate with 600 paper until all the marks were gone. There was a service bulletin about the gasket being too thick so I reused the old one. My oil pressure went up to 12lbs at idle and would break 20 at reves. One of our members pointed out some on eBay so I bought a few. 
 

here's another one. 
NOS Kawasaki #11009-1023. Oil Pump Gasket. KZ1000 A1. 11009-1023.
Im working up another pump and will install it soon. 
Steve

You have to watch those gaskets, most if not all I have seen and bought on ebay are way too thick. I ended up making my own using parchment paper which is about .0025 thick. You may need to cut and use two gaskets to get the proper clearance. I used the ones I purchased on ebay as the pattern and still have them for future pump rebuilds. 

We have a NOS oil pump gasket that is literally paper thin.  Haven't measured it but, Cra-Z1's .0025 spec sounds about right.  Good idea about the parchment paper as gasket material.

RTV silicone might be worth a try.  Test before applying sealant by assembling bare & dry to make sure it spins freely.  Considering how flat the pump body and side cover are machined, a very thin wipe of RTV could be used on the cover plate, avoiding the gear area by a few mm.  Think thumb pressure wipe, leaving just a barely visible sheen of sealant.  And read the directions; apply RTV, assemble only finger tight, wait ~1 hr, or so, apply final torque.  Then give it a test spin.

Good Ridin'
slmjim & Z1BEBE

Parchment paper looks like the route I'll most likely use since you never know what you'll get when you place an order for a new gasket.  When I looked into gaskets according to the service bulletin, the only part number that I could find to order was for the standard thickness.  It seems that no one had ever heard of the thinner one, at least I could never find any listing of it online.

As far as going the RTV or 3Bond route, what is the torque spec for the oil pump cover plate?  Did I miss that in the manual?  I did notice that with a bit too much torque the gears would bind.  BTW, this is an early style pump that uses a gasket like this:

 

As for the oil, I think I'll try the K-Tech for its claimed "Protects against excessive viscosity decrease at high temperatures".  If this clears up the issue, then perhaps I can put off tearing into the engine until a future date.

Thanks everyone!

I think you can’t get much better than oil that can sustain a diesel over 500k miles. Good enough for me. 

The manufacturers buy their branded oil from a variety of suppliers. Among the best motorcycle specific oils are are Red Line and Mobil VTwin oil.

My father was an airforce mechanic in WW2.  His initial training consisted of filing a block of steel until the opposite sides were parallel to within 1/1,000 of an inch.  He also said the reason they did that was because the heads on Merlin Spitfire engines were hand fitted to the cylinder blocks without gaskets.  

The oil pump runs in the sump and I wonder if it can be run successfully without a gasket?  Leakage would simply go back to the sump.  The only issue might be too tight side clearance.

hardrockminer wrote:

My father was an airforce mechanic in WW2.  His initial training consisted of filing a block of steel until the opposite sides were parallel to within 1/1,000 of an inch.  He also said the reason they did that was because the heads on Merlin Spitfire engines were hand fitted to the cylinder blocks without gaskets.  

The oil pump runs in the sump and I wonder if it can be run successfully without a gasket?  Leakage would simply go back to the sump.  The only issue might be too tight side clearance.

Automotive oil pumps, the type internal to the engine, typically don't have any gaskets.  They use tight fitting parts, and as you say, if any small leaks occur, it's internal to the engine.   

hardrockminer wrote:

The oil pump runs in the sump and I wonder if it can be run successfully without a gasket?  Leakage would simply go back to the sump.  The only issue might be too tight side clearance.

If you look at the service bulletin 4/900-06, page 2, it states in one of the photos "GEARS SHOULD PROTRUDE SLIGHTLY ABOVE GASKET SURFACE", so it seems that KHI has engineered in the gasket.  I wish that weren't the case, it would make life much easier.  Oh well.