I just took a look at the Atlantic Z car club page about the Tokico strut replacement. They're refilling the strut tube with fluid for the Tokico's. The KYB instructions (for the GR2's that I am inserting) don't say anything about this. Do only the Tokico's need strut fluid?

They are probably talking about adding about 1/2 cup tranny fluid to the strut tube before you insert the strut cartridge. I don't think you will find this information in any manual. The reason for doing this is it the fluid helps disipate the heat that is created by the strut during operation. The fluid acts as a conductor spreading the heat to the strut housing. It also acts as a rust inhibitor. Do a search and you will find several threads about the subject.

Yes, you need to add fluid for heat transfer. Any lightweight oil will work. The only exception to this is Bilstein dampers. I had them on a 240Z and they specifically said not to use oil. Bilsteins are upside down monotubes though, so it makes sense that they wouldn't need oil in the housing.

Don't use a 1/2 cup or you'll make a big mess. One or two ounces is plenty.

It's probably not important for street driving, as seldom will you get the struts hot unless you're on the track.

The Z will be street only. But, if it's not going to hurt anything I'll add it to the strut housing. Thanks guys, again.

Definitely won't hurt a thing. Makes it a bit messy next time you do the struts, that's about the only downside. In fact, I seem to recall that even generic Monroe and Gabriel cartridges way back in the late '70s would recommend 2 oz. of oil in the tube.

When I was removing the orginal struts I did take a nice bath in the old fluid. I thought I drained it all out until I pushed down on the old strut rod...

  Arne said:

Don't use a 1/2 cup or you'll make a big mess. One or two ounces is plenty.

Thanks for clearing this up Arne, I couldn't remember how much fluid to use, I do remember it wasn't much and it makes a mess if you use too much.

When I did this for a living, I used to simply leave a teaspoon or so of the original oil in the tube.

As a side note, I recall that we couldn't do this on old Volvos - mostly 240-series. Those cars used regular cartridges from the factory, and the strut tubes had a hole in the bottom. No idea why Volvo did it this way, but moisture could get in there through the bottom hole and rust the cartridge into the tube. Very ugly...

Adding to this:

OK, the KYB-GR2's don't fit back into the original strut cylinder (that the stock strut was inside of where the oil 'was') that fits into the entire strut assembly. The KYB's diameter is a little larger than the strut cylinder. The piston rod guide that had the o-ring on top of it that actually kept the oil between the stock strut and the cylinder doesn't fit. The KYB comes up to the top of the strut assembly with just enough space for the gland packing ring (KYB's gland packing ring) to secure the strut inside of the assembly. There's no way to add oil (I bought some $2 tranny fluid, no loss) to the strut assembly with the KYB's. I'm guessing or thinking, sometimes those are the same with me, that the KYB's are 'all good' without any additional heat transfer fluid between them and the strut assembly. OK, done...I'll take JW Black and water in a tall glass. I'll open the Blue Label when the car is done.....might be 70 year old scotch by thenROFL

I'm an idiot. I just took another look at the Atlantic Z Car page strut replacement info..the gland packing ring holds the fluid in. I heard that...I already said that I was an idiot.

When I was stationed in Italy, and had the local shop weld up my strut tubes, after sectioning them for coilovers and shoter inserts, they heavily coated the outside of my new inserts with bearing grease. Just thought I would throw that out there. I myself use Redline MTL...always have some around and just a little will do the trick.