S60 Track Project transmission oil HELP NEEDED

Hi all, long time reader, first time poster, having a few issues with my newly acquired 2002 S60 2.0T. Have done £1300 down the bloody thing since getting it for free off a charitable family member (had to scrap my busted-ass 1999 V70 as there were just too many things to warrant fixing), in order to get it ready to spank my mates in their Type-Rs at a track day as soon as possible. Have replaced all fluids (except trans), and have fitted 336mm XC90 brakes, EBC discs and yellowstuff pads with 17" T5 alloys over the top and fresh rubber. It has had a brand new clutch and flywheel, new fuel pump, and a muffler delete for extra knicker-dropping power (I have yet to determine if it works but it sounds f*****g naughty). Have got a remap and BC racing coilovers planned, along with some weight reduction before first send, but have encountered a small issue before then (it might be a huge issue tbh but we'll see won't we?)

Basically, I'm having issues shifting from 1st-2nd under heavy throttle. It's fine if I take my time and shift below 2000rpm (DMF takes ages to get back down to low revs) but if I try and give it the cane it just will not go in gear. No grind, no slip, just nothing, until I relax, let the revs settle, and then slide it into gear. It's the only gear it does this on (occasionally into reverse when hot but not often) and it's pretty weird tbh. Thought my synchro might have died between 1st-2nd but it doesn't even like shifting with a rev match, although it's fine when heel-toeing back down through the box.

My question is this: my mate who is a qualified mechanic had recommended that I find out what trans fluid gets used for race/project applications in general, and I want to know if there is anything you guys know of with better heat dispersion than standard. Not really bothered if it's louder or anything with a different fluid, she's loud enough for me not to notice, but am wondering what trans oil high performance guys go for? And also, whether it's worth even bothering to drop the fluid or just bite the bullet and bin the trans and get another. Have found several M56 for dirt cheap so assuming it just fits then could probably nick a ramp for the day and do it myself, although reluctant to drop the subframe and p**s about all day if I don't have to.

Anyway, have basically written an essay there, cheers for anyone who has made it to this point and feels like responding.

TL;DR: I NEED TO KNOW WHAT PERFORMANCE TRANS OIL GOES IN A VOLVO S60, AND IF THAT WILL EVEN HELP WITH THE ISSUE I'M HAVING

Cheers for your time

Never mind, have figured it out. After speaking to a couple of Volvo dudes they recommended I pop the airbox off and just have a check of the linkage cables. The plastic sheathe around one is completely snapped, and has left the cable itself a bit baggy, which would explain why it isn't pushing into gear in 2nd, 4th or reverse properly. The actual cables themselves will probably be replaced when I find a suitable pair this week, and will see if I can get to it on axlestands on the driveway, so wish me luck. Will be replacing fluid with decent race fluid next week as well, but will probably speak to Read View before I do to see if they've had any race projects in before and therefore will know what oil to go with.

Cheers to anyone who read this either way.

Keep us posted on how it all goes, plus some pics of your car.