Kev I have had so many senders fail with these 3800's... Its almost annoying...
The van was good till I accidentally broke it... Had to replace it lasted a few months and wigged out... I replaced it again and then it never showed more than 45 Psi.... Replaced it with an AC Delco that told the truth for 4 or 5 months then wigged out...
The exact same goes for my 95 Bonneville...
Funny story... I put a trans in a friends car( 93 LeSabre with the Vin L ) I broke his oil pressure sending unit... I replaced it and its been 100% perfect for 2 years...LOL
30-40 Psi hot idle and 60-65 Psi at 1850Rpms...
The vans series III 3800 is actually doing 65-70 Psi at road speed and 35-40 at idle.. I have only had one sender show me this and that was the AC delco..
For what ever reason I have no luck with the oil pressure senders... The one on the van is fritzing out again... Now and again it will show me 70 Psi... The 95 Bonnie stays between 40 and 100 Psi
Oil pressure gauge on the GM's is funky at best imho...LOL