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2014 Forester 2.5i
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Discussion Starter · #1 · (Edited)
Want to tow a 800 lb. (loaded) Runaway Camper, Starter model. Has been mostly highway with maybe 200 miles of demanding mountain pass driving (?) and maybe a thousand miles less-than-gentle dirt road driving. One time in steep rugged mountain pass driving 2-3 mph the CVT fluid temp warning light came on steady for maybe five minutes before i could get off the trail.
After studying the CVT drive Chain/cable/link mechanism with its little traction grooves machined into the 399 keys, my question becomes" How much wear has reduced those little traction grooves, how much life is left in them?" How tough/resilient/wear resistant are they?
I have had the CVT fluid checked at the dealer who reported the fluid looked like new.

Any other tests to estimate the effect of towing a light trailer over interstate, paved and dirt roads?

Thank you for your thoughts and consideration!:thumbsup:
 

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2013/14 2.5i-L CVT
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After studying the CVT drive Chain/cable/link mechanism with its little traction grooves machined into the 399 keys, my question becomes" How much wear has reduced those little traction grooves, how much life is left in them?" How tough/resilient/wear resistant are they?
Are you referring to the grooves seen in Van Doorne push type CVTs? If so, the Subaru CVT pulleys have smooth sides and the steel chain pulls, not pushes with no mechanical interlock between the pulleys and chain. Force is transfered between the pulleys and chain by friction alone.

My understanding is that the CVT fluid stiffens when under pressure such as when trapped between the cones and chain elements and this increases the friction up to the level required. This is why the the higher torque CVTs for turbo, 6 cylinder and diesel engines use a different fluid to the 2.5i N/As.
 

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2014 Forester 2.5i
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Discussion Starter · #3 ·
Thank you for your information. If the fluid is formulated to thicken under shear, does it wear out? How often should it be replaced?

Thank you again.
 

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2013/14 2.5i-L CVT
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If the fluid is formulated to thicken under shear, does it wear out? How often should it be replaced?
Subaru says it should last the lifetime of the car in normal use, but lists several severe use conditions, including regular towing, under which it should be replaced at 25,000 mile intervals. Lab tests submitted by some members - for example GeoJosh's - suggest it should be good for 100,000 miles/160,000 km.

Fwiw, I've towed my 2,000 lb boat for about a cumulative 12,000 km/8,000 miles without any problems so far.

Note: Australian Foresters come with an OEM CVT cooler which might increase fluid life. OTOH, our temperatures are often much higher than are typical for much of the U.S., especially the northern states where Subarus are most popular. In summer it is not uncommon for maximums here to exceed 100° F daily for a week at a time.
 
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