Sometimes in two wheel drive when the rear wheels are spinning the front pops into four wheel drive momentarily without the AWD switch being on.

I believe this is the reason that they upgraded the pinion plate to steel on the newer models, to prevent damage and why there is a cecco aftermarket part as well. I'm not sure why it happens but lots of reading on it in past threads.

Oil in the front gear case either too heavy or contaminated (usually by water)

It is a concern - you should try to avoid actions that cause the problem - it may damage the gear case either internally, externally or both. Change the oil in the gear case and fill with ATF to see if that eliminates the problem.

latebird said:

Oil in the front gear case either too heavy or contaminated (usually by water)

It is a concern - you should try to avoid actions that cause the problem - it may damage the gear case either internally, externally or both. Change the oil in the gear case and fill with ATF to see if that eliminates the problem.

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Latebird - are you suggesting that the Polaris demand drive fluid is too viscous and that most times in the cold ,ATF would be better - especially in really cold and not just cool temperatures?
If that's the case - what type of ATF (there are literally dozens of different ones made specifically by and for different makes and models of vehicles).. is there one brand or type better suited to replace Demand Drive Fluid better than all others?
I'm asking as I am about to change the front diff fluid in a couple of days in my '18 Sportsman 450 on tracks for the Winter - where it often gets down into the -30 range (F degrees)..
Also - if that is the case, would the same ATF be better or preferable even during warmer months of the Summer here - over the Polaris Demand Dive stuff as well?
Thx - Randy

I use ATF type F or Mercon almost exclusively - I use Honda two stroke transmission oil if ATF type F is not available

latebird said:

I use ATF type F or Mercon almost exclusively - I use Honda two stroke transmission oil if ATF type F is not available

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Is the Type F Mercon preferable in all (but especially in really colder) situations - over or just a cheaper alternative to the Polaris Demand Drive stuff in your estimation though?
Randy

Type F is formulated not to promote slip of the clutches of automatic transmissions - type C does promote slip - really does not make a difference when lubricating between the faces of the gears, but I have all Ford products and the type F works equally well in my dirt bike transmissions. So I have plenty of it on the shelf of my garage. Polaris DDF may well be ATF with a different label, but I find ATF type F works as well as DDF and AGL - so one oil for two applications.

latebird said:

Type F is formulated not to promote slip of the clutches of automatic transmissions - type C does promote slip - really does not make a difference when lubricating between the faces of the gears, but I have all Ford products and the type F works equally well in my dirt bike transmissions. So I have plenty of it on the shelf of my garage. Polaris DDF may well be ATF with a different label, but I find ATF type F works as well as DDF and AGL - so one oil for two applications.

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Thanks I may consider using the F instead - I also have some PS-4 engine oil - but have heard others say Klotz or Amsoil is better - do you have any idea if that is true and if so which one would be the 'ultimate' type and grade to use over the PS-4 stuff in your estimation for a 450 HO engine - especially for cold Winter usage?
Thx Again..

Realzed said:

Thanks I may consider using the F instead - I also have some PS-4 engine oil - but have heard others say Klotz or Amsoil is better - do you have any idea if that is true and if so which one would be the 'ultimate' type and grade to us over the PS-4 stuff in your estimation for a 450 HO engine - especially for cold Winter usage?
Thx Again..

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I use Klotz not because it's better, but because it's what I like.

I use Klotz 15w50 in my race bike and my ATV - I use Honda GN4 10w40 in my 1100 Shadow and CBX - I use Castrol 20w50 in my Triumph 650 Bonneville and Harley Sportster - I use the cheapest 5w20 mineral oil that Quick Lube offers in my cars and trucks