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[Brynjaminjones]

I'm trying to find the right oil for the 360 V8 in our Wagoneer and wanted to get a few opinions.


I changed from 20w50 to 10w40 because I used to get some rattle on startup. This fixed that, but now the pressure goes lower than I'd like when I've been on the motorway for a couple of hours.


It looks like I need something thinner when cold but thicker when hot.
I've found some 5w50 that sounds like it might do the trick. What's the opinion on this? Is there any concern with going this thin when cold?

[Dave69]

thinner when cold..thicker when hot??  changing the laws of physics now?

the lower the first number the thinner the oil hence your getting lower oil pressure on runs, thin oil is for modern engines not your old big V8

w = winter

the second number is the viscosity at 100 degrees C so as with the first number the lower the number the thinner the oil

based on that if you want it thick when hot the you are looking for an oil of 50 or above or go to a mineral oil.

you could inspect the oil pump for effectiveness.

[Brynjaminjones]

Cheers for that Dave. I could have made it a bit clearer what I was saying - I wasn't intending to say thinner when cold than hot! 

What I actually meant was I need thinner when cold than 20w50 but thicker when hot than 10w40. 5w50 seems to tick both of those boxes but I was wondering if the 5w part might be a little extreme for these old engines!

It definitely seemed happier when hot on 20w50 and I know lots of you have recommended it.

On the subject of the oil pump, I am aware that the timing cover will need some attention at some point and is probably the cause of my low pressure.

[5536paulj]

Bryn,
There's a 0/60 mobil oil for motorsport that's good for classics

And Valvoline vr1 20/50 is good for old engines, has lots of ZDDP in it, good for tappets etc.

I've been using 20/50 from Comma for a while with no issues.

Don't make any oil pressure assumptions until you've checked it with a proper mechanical gauge..

Paul

[Brynjaminjones]

Thanks Paul.
I did run Valvoline VR1 20w50 for about 3,000 miles and it was good when hot, but the rattle on startup terrified me. The 5w50 I've found is also Valvoline VR1 which is why I'm considering it.

You do also make a very good point about verifying the oil pressure. I wonder sometimes if my low voltage issues could cause a low pressure reading.

[wildwood]

Could it be that your hydraulic lifters are ..
A. worn
B. Coked up so the oil takes a times to charge them up.....

Cheap to do......

Had a Rover (cough cough) V8 that rattled like a bastard.....replaced the lifters and all you could here was induction and exhaust.....job jobbed....

Just a thought.... Or have we been here before??.

[5536paulj]

Bryn,

Wheeler Dealers tonight is about a Wagoneer, you may pick up some tips!! on Discovery Channel in 10 mins

Suggest you buy / borrow a mechanical gauge, doesn't have to be in the dash, could mount in the engine bay.I have one of these, and is cheap enough and works fine

https://www.jjcraceandrally.com/autograss/mechanical-gauges/tim-oil-pressure-mechanical-gauge-capillary-type-52mm