1 Lucky Texan

that would be a welcome idea(easy to fix) - but it's actually easier to underfill - that's why you have to check that fluid with the engine idling or it will show a level 2" higher than required. It IS important to remember - you can only drain about 1/2 the total volume. Might need to check the radiator - maybe coolant pressure pushing coolant backwards thru a hole in the trans cooling coil? It's theoretically possible I guess, just never read a confirmed failure like that. Or, is it possible trans fluid is being put into the front diff and it is puking? Doesn't seem likely - maybe the trans pump got cracked - easy to do pulling the engine in that last 1/4" from what I have read. It must slide together - if you pull it together with the bolts, something will break inside....?

the typical 5 spds are strictly mechanical. THe STI has some odd DCCD, or, some models did - still, don't think there was a FWD option on that one either. The 4EAT has an electrically controlled set of hydraulic clutches so, the fuse tells the TCU to keep the wet clutch pack disabled - no power to the rear wheels.

oh, isn't it a manual? if auto, definitely try the FWD fuse position. (not accustomed to the term gearbox for auto trans I guess - but, OP is in Spain so.....I should have asked)

well, axles will last a long time, even after they begin to click - but it's a gamble on how long. re-booting some from a junkyard that probably haven't split yet, means no exposure to grit, water, etc. so, more likely to last a long time. if you want to reboot your clickers - try swapping sides with them , MAYBE you'll get longer service using the wear surfaces previously pushed on just going in reverse.

torque bind in manual transmissions seems to be temperature dependent so - it seems the viscous unit in the center diff may be bad. the unit can be repaired, but often folks will get an entire gearbox from a wreck - often with lower miles - and swap it in. any replacement gearbox MUST have the same final drive ratio as your present trans. (or, rear diff must match the new trans.)

check Craigslist for someone 'parting out' a car? also;https://www.lkqonline.com/?ref=g-ppc&gclid=CjwKEAjw1_KwBRDEz_WvncL4jGwSJAAEym0dqYUvy2qMpatc9qMtG4LhdpACML_mP-CkAnAQW6_h-RoC0S_w_wcB#!/

I was just wondering if torquing with the car's weight on the ground 'could' lead to repeat failures?

not sure the HBAs are subject to the same forces but one thing I recall, an FSM section on bearings warned against torquing the axle nut with the wheel on the ground. I have put a large screwdriver to 'buck up' against the caliper when I torqued the axle nut.

do the pads move freely in the caliper? some folks have had to file/grind pad backplate tabs/ears smaller. Or maybe rust in that area could cause binding?

I will say, it seems our soobs suffer more than a fair share of wheel bearing issues. one reason why I feel Timken or other name-brand replacements are fine - I see no indication OEM are anything special.

do a drain/fill and use the conditioner. Other than that, it's risky. KEEP IN MIND - you are due (overdue actually) for a timing belt service if it hasn't been done(105kmiles OR 105months). You could combine that service with cooling system service fairly easily. if you decide to change the thermostat since the coolant system is empty, you MUST only use an OEM-style t'stat. (there is a Stant Xacstat that seems to work, but do a search for the correct part number. - you could just re-use your old t'stat, might be a good idea to test it on the stove in hot water - oh, uh-NEVER let any mammal you care about consume even a small amount of antifreeze!) might be a good idea to get a new radiator cap too. refresh the whole system. many folks pull the overflow bottle and clean it out. Cut the tube in there at a 45* angle on the bottom to help reduce sucking any contaminants back up to the radiator neck. Consider putting a tiny clamp or a coupla zipties on the small tube at the neck too. you can find plenty of threads on cooling system maintenance of course, people have done all of the above and still experienced bad HGs. particularly with used cars - you don't know if an engine was overheated or not.. But, typical subaru 'blown' HGs push all or most of the coolant into the overflow bottle and most will have active bubbling of combustion gases while failing.

eh - not hard, messy. Most folks only need to reboot the inner joints so, outers are trickier I think as they need to come off? maybe search here for a thread about it or watch a 3-4 youtube videos - most half axles follow similar construction. If your outer is making noise, probably time for a new axle anyway. Or, I think you can find Febest brand outer joints on Amazon. dunno if replacing just the outer would lead to vibration at idle or not..... also, our H6es have valve cover leaks too. You might look for that. I GENTLY re-tightened all the VC bolts I could get too - one or 2 seemed only fingertight. Don't twist too hard though! the oil cooler adapter is another 'fairly' common oil leak. ALL oil leaks 'could' be made worse by gummed-up PCV valve.

smell when parked possibly due to grease from split axle boot. many people advise getting a used axle from car-part.com or LKQ, etc. and re/greasing-rebooting yourself. Or find friendly mechanic to do it - you will be MUCH more likely to have a good axle if you stay with Subaru. new are very expensive, but rebooting a good one from a wreck will give great service. MANY people have had aftermarket rebuilds axles cause vibration - plus a short life. (I got vibration from using one) some people report excessive oil consumption from bad/gummy PCV valves. cheap/easy to replace or clean - clean/replace the hose too if it looks bad, do not run that engine low on oil!

good to read Timken is OK on soobs. The one I put on my daughter's Impala (hub bearing assembly) has been fine. (it was even well packaged and impressed me as to surface finish and general appearance too.)

can you be more specific about this 'tightening-up/shrinking' statement?

I don't think 'blown' HGs are inevitable on an 06 but, external seepage seems pretty common. the Subaru conditioner is meant to stop/slow external leaks - everywhere,... but of course HGs were/are the main reason Subaru offers it. it was never meant to help with internally blown gaskets. don't use 2 bottles, don't add a bottle if there's the chance a dealer or prev. owner added one, don't combine other stop-leaks, DO NOT dump it in the overflow, go by the instructions. people have reported it helping.

if it's an older car, might be the last knock sensor it ever gets - I might cut the other conn off, prep all 4 wire ends, crimp butt splices on, pack them in dielectric grease and wrap in tape. EDIT; wait, if it's a stylle of knock sensor that has its connector molded on - no pigtail, might need to visit a junkyard and do as suggested, solder and shrink-tube the connector onto your harness. Keep the new length as short as possible - I think KS signal might be confused if a lot of electrical noise gets on the wiring.

Have you checked the front differential fluid level? Anyway you may need a mechanic to drive/check-out the car.

disconnect the exhaust - might be clogged. Or check for that with a vacuum gauge.

if they are original, I assure you they are 'bad'. (struts do often deteriorate slowly, but if you regularly drive on bad roads, for 185K miles, no way your struts are working well.) doesn't mean something else isn't wrong - bad diff mount bushings and rear bushings for the front lower control arms def. need inspecting. maybe post your city in a new thread and ask for a shop near you. get some experienced eyes on your suspension parts.

any other symptoms? noises? any work done or wrecks before this began? any pending codes stored by the ECU?

plasic tanks can leak where they are clamped to the fins/tubing.('core') maybe a pressure test would find you have a leaky radiator?

those can be swapped (along with the crank seal) during a timing belt service if old and certainly if leaking. what car/engine?

you never hear the noise at idle? would the sound change if you lightly engage the brakes? have the brakes ever been changed on the car? could be the caliper(s) are dragging.

was the filler tube rusted thru? there are probably several places you could get a decent filler cap from - even Amazon. Junkyard caps won't be much better than yours but.....if you have to save every penny.....