I Have Twin 525sc In My Boat,yestarday I Took The Wife For A Ride And Everything Worked Great,all Guages Equal,then Went Back Out In Yhe Afternoon And The Oil Temp On The Starboard Kept Climbing Up To 230 With The Port Staying At 190,water Temp On Both Engines Stayed At 150,is There An Oil Tstat Located In The Oil Filter Housing That Could Be Going Bad??any Other Ideas Would Realy Be Helpfull!!

dont think you have stats in your oiling system,sounds like an impeller...

I believe ALL blue motors have oil thermostats. They have changed some over the years. Some were in oil adapter, now I think all are in oil filter block.

Impellors circulate water. First change in gages would be WATER TEMP. Significant change in water flow and/or temp will affect oil temp. Remove and backflush oil cooler water portion to check for debris from impellor.

Stuck oil thermostat will result in hotter, dirtier oil.

Swap oil filter blocks, to see if problem moves to other motor.

Latest 525 SC oil system. http://www.mercruiserparts.com/Show_...ER+AND+ADAPTOR

The Motors Are 1998,the Water Temp Stayed Around The Same As The Other Motor Of 150,the Motor Still Ran Good,its Just The Sudden Change From One Run To Another That Is Disturbing.i Looked Around The Oil Filter Block And Did Not Find Any Place A T Stat Could Be,only 2 Npt Plugs,2 Lines And The Filter,could It Be Any Place Else?

This is late '97-up. There is an oil cooler for '96, early '97, late '97-up and they all look the same.
http://www.mercruiserparts.com/Show_...ER+AND+ADAPTOR

The best way to verify that it is the oil thermostat, is to swap between motors. They are in the block the oil filter is mounted on. Swap the blocks, keeping filters on original filter blocks.

This will be a mess. Have you check for water restrictions in oil cooler?

ck ground wire to it