Bypass Oil Filtration?

P.P.S. Regarding your idea of using a Inverter coolant pump to pump the ATF, I suspect the higher viscosity may be a challenge for it. Still think increased Inverter circuit cooling might be better. Does the ATF actually get too hot? Remember that the heat capacity (and conductivity too?) of water is much higher than that of oil (and ATF?), so cooling the coolant more seems to make more sense to me. That said, if the coolant galleries within the motors are transferring heat up near their theoretical limits, increasing the cooling capacity of the rest of the system isn't going to help much. OTOH, maybe all you need to do is boost the coolant flow rate through the system? The design size has probably been optimised based on the 12V Power Consumption, and maybe a bigger circulation pump and larger diameter hoses would achieve the result you are after?

 

Hi again John,

Good point! I'm not too familiar now with the MG cooling system, but I was under the impression that where were coolant pipes running through or around the motors. Is that the situation, do you know? If so, it seems to be the best way to get the heat out, but if as you suggest, it's via the ATF to the case, then I would agree with you 100%. Cool the ATF directly as well!

 

One other point:

The Transaxle is sealed to prevent water vapour getting in, due to the High Voltages present. It has a one-way relief/purge valve which allows internal air/vapour pressure to escape, but does not allow (potentially [invariably? in the UK] moist) air back in. Thus, the transmission housing holds a partial vacuum at all other times. Probably not sufficient vacuum to be a problem with crushing hoses, but running hoses, pumps etc carrying ATF around outside the transaxle will provide increased opportunities for moisture penetration - even by osmosis through the hoses, not to mention air leaks in pump seals, etc.

I think I might've put myself off the idea of External ATF Fine Filtration now...

The ICE is still a clear candidate.

 

Now THAT'S What I call an answer! Many thanks ETC(SS). Close to what I was after.

My reason for contemplating Bypass Filtration isn't / wasn't to avoid engine replacement though. My interest is in avoiding the dreaded early oil-burning issue that I have read about here and heard about locally. I don't know what the cause of it is, and maybe the truth is it's the exact opposite of wear. Maybe it's the result of overly gentle driving, causing glazing of the bores. That will produce excessive blow-by and oil consumption. But a new set of rings and a cylinder hone - does that qualify as an engine replacement?

Anyway, here in NZ, we have fleets of Prius G2 & G3 taxis. Though I haven't seen a lot of evidence of this myself, I have heard from a reliable source (a Toyota mechanic) that they have a tendency to start burning oil after a while. That bothered me, because I would have thought taxi operation, especially in a country with serious urban sprawl, would have been the ideal work for them. Maybe not.

Japanese engines have long been admired for their robustness and ability to withstand neglect and abuse, and Toyotas are no exception. But when I see fellow Prius drivers around town, they are all driving so sedately, so daintily, taxis included. I guess they are trying to save fuel.

I can't be bothered with that. The car saves fuel regardless, so long as one gives it enough time to regen during deceleration. I can't be bothered with gliding (never much opportunity here anyway), so I accelerate "robustly" and try to start slowing down early. And I have been utterly AMAZED at the number of idiots and morons on the road, who, like me are approaching a red light (for which I am busy slowing down in regen mode), but who will make a point of changing lanes and accelerating past me, just so they can show me their brake lights as they haul up for the same stop light that I started responding to 100 metres back. I frequently end up, pulled up beside them, and invariably make a point of looking over, but they almost never look back. They keep their eyes straight ahead, and I wonder if they know they are idiots, or are just too stupid. I guess watching moving traffic IS pretty interesting...

Anyway, I give other cars drags from the lights, throw her around corners and generally try to show other drivers that a Prius is NOT just for pussies and greenies. Call me contrary. That's why I was interested in Bypass Filtration.

P.S. I tend to agree with you that 10,000 miles seems a very long OCI. However, having just changed my G2 oil after 10 (11?),000 km, I was very impressed at how little discoloration was present. Any other non-hybrid engine would have dirtied the oil much more in this time. I believe this shows how much of the oil contamination occurs during idling. This actually does make some sense. If you have had the opportunity to study engine blow-by, you would probably agree that there is a hugely disproportionate amount during idling. AIUI, this is because at idle, the combustion pressure are very low, just enough to keep the engine turning over. (If you run an engine with no muffler, you'll hear the difference - almost no noise at idle, but huge noise under load.) Anyway, under load, the compression rings flex and expand due to the higher gas pressure, and make a much better seal with the bore. There is much less blow-by, compared with the power output. So, simply cutting out the idling means all that idle-generated blow-by, which contains many more contaminants due to the poor combustion that occurs at idle, does not happen. On that basis, the extended OCI, MAY be justified. But that's just a suggestion, not even my opinion!

 

Hi Fred_H,

Exactly! For now I've settled for a Z432HE Full Flow Oil Filter.

A Great graphic...

And thought-provoking quote. However, there never was any possibility of a lack of stone...

With the likes of G.W. Bush and friends pushing the oil wagon, I can't see any better alternative. I mean, would you want GWB and cronies in charge of anything more dangerous than something so stable that it has been lying there maturing, under the ground, since dinosaurs roamed the Earth?

GWB and Nuclear Power??? God Help Us!

Regards,
Al

 

Thanks for your input. I guess "fleet-use" means driven mercilessly - and in some cases, such as some rental car fleets, poorly maintained?

Without doing more research here, I'll guess that the people here who have reported oil burning have bought used cars with poor maintenance histories. But your comments are very reassuring.

 

Hi John,

Wasn't trying to be smart - I understand what the mirror is about - just thought it looked like a good design. Easy to put on and remove, without permanently altering the car. Yes, I've driven those narrow country lanes you have in the UK. One learns to be a better and more considerate driver as a result.