Oil Change?

[BIG GRINDER!]

Hi
I did my last oil change myself and had no problem
I posted on my local scooby site and they a talking about disconecting the crank sensor during the change.

Subaru's own workshop manual does not mention this.

What is the best way to do an oil change??

Kev

[bob]

Drain oil. Remove filter. I usually leave it draining for about 15 mins. Always fill the oil filter with new oil. Reconnect new oil filter. Fill with oil to right level. Disconnect crank sensor and crank engine for about 30 seconds. Connect crank sensor and start engine. Switch off and recheck oil level . I always use Silkolene 10/50.
Most Subaru garages do not bother with the crank sensor method. Perhaps this is why a lot of scoobs go bang not long after having a service.

[stumeek]

Excuse my ignorance, being a newbie to scoobs, but why disconnect the crank sensor for an oil change, is it something to do with the big brother ecu? Does it monitor oil quality and need resetting?Or is itj ust to ensure the oil is pumped around the engine before it's started. I do appologise in advanvce for my lack of intelligence, and possible stupidity of this question.

[bob]

Originally Posted by stumeek

Or is itj ust to ensure the oil is pumped around the engine before it's started. .

Thats about it... Surprising how quick a bearing will pick-up when little or no oil is going to it for a few seconds.

[BIG GRINDER!]

Originally Posted by bob

Drain oil. Remove filter. I usually leave it draining for about 15 mins. Always fill the oil filter with new oil. Reconnect new oil filter. Fill with oil to right level. Disconnect crank sensor and crank engine for about 30 seconds. Connect crank sensor and start engine. Switch off and recheck oil level . I always use Silkolene 10/50.
Most Subaru garages do not bother with the crank sensor method. Perhaps this is why a lot of scoobs go bang not long after having a service.

Hi
Thanks for that info. I use the the Silkolene 10/50 as well.
Personally I find it strange that scooby's should go bang after a dealer service.

Cheers Kev

[bob]

Originally Posted by BIG GRINDER!

Hi
Thanks for that info. I use the the Silkolene 10/50 as well.
Personally I find it strange that scooby's should go bang after a dealer service.

Cheers Kev

On S/net back in 98-99 we had a thread about when engines went pop and why.
It seemed about half went pop when coming off throttle after a high speed run.
The other half was a short time after a service... Most were N03 big ends.

[uk dave]

The thing i dont get about the crank sensor thing is that surely whats the difference between ur car standing overnight only to be started from cold totally and then tick over at high revs as soon as it starts and the fact that most oil changes or at least the ones me and my mates do are done whilst the engines warm(not hot) i always leave them to drain as long as possible and refill the filter first then top oil up,and because the engines still warmish doesnt tick over highstraight away anyway,done about 5 changes on mine and about 4 on me mates scoobys and never had a problem (always use silkolene 15w50 pro r in case anyones interested)then when it needs proper service goes to rcms where they use the same oil.

[bob]

Originally Posted by uk dave

The thing i dont get about the crank sensor thing is that surely whats the difference between ur car standing overnight only to be started from cold totally and then tick over at high revs as soon as it starts and the fact that most oil changes or at least the ones me and my mates do are done whilst the engines warm(not hot) i always leave them to drain as long as possible and refill the filter first then top oil up,and because the engines still warmish doesnt tick over highstraight away anyway,done about 5 changes on mine and about 4 on me mates scoobys and never had a problem (always use silkolene 15w50 pro r in case anyones interested)then when it needs proper service goes to rcms where they use the same oil.

When car is left overnight the oilways and pump are still full resulting in instant lubrication. On a oil change the oil ways and pump are emptied. When refilling air will be in the pump and oil ways this air has to be pumped out before the oil is recirculated. So cranking the engine will purge the air from the system. If you just start the motor after oil change who knows how long it will take to purge the air before the oil is recurculated.

[uk dave]

so presumably then the oils held in the oilways and pump by the filter still being attached yes,otherwise there`d be no difference surely if your refilling the filter anyway.(excuse my ignorance just curious.)

[bob]

Originally Posted by uk dave

so presumably then the oils held in the oilways and pump by the filter still being attached yes,otherwise there`d be no difference surely if your refilling the filter anyway.(excuse my ignorance just curious.)

Drop a pump in a pond and switch it on...Most the time the pump will not pump as air is in the system if the pump does work it will take plenty of time to spurt out the air before running at full pressure. Put a pump in the pond and bleed it by removing the air and pressure will be up almost straight away.

When draining the oil the pump empties as well, when you refill with oil the oil does not always fill the pump even though the filter is full you have air between pump and filter as air is holding the oil back. Spin the pump to remove the air and fill pump with oil.
So spinning the pump by starting the engine COULD starve bearings for a few seconds.
Spinning the pump manualy by cranking will remove any air in system.
We all know how small scoob big end bearings are...

[uk dave]

cheers bob for that best explanation for it ive read on any scooby forum.

[BIG GRINDER!]

Hi
Did another Oil and filter change on the 28th. Didn't disconnect anything. No problems. Cheers Oilman ;-)

Happy New year to all.

Kev