@Dave03S that is so crazy to me that they ran 5w-30. It was like they were sabotaging their engines.

I'm sure mine has the same history. It has reman heads, new head gaskets with ARP studs, new rockers, and lots of recent oil changes with Rotella T4 15/40. Might switch to Valvoline 20/50 VR1 for the increased ZDDP.

I was told it had 80k miles on it. So I am hoping for the lifespan out of it that you got. About to install the Inline stat from @Extinct to get the temps even lower. My OE 180 is working well, especially once I learned to run around town in 3 instead of D. Keeps the revs a little higher and more flow from the water pump. Keeps the temps a little lower.

 

I have to say like anything this old prior maintenance is everything,having a basically new cooling system I am looking at replacing the the lower Y with an aluminum part,and adding the inline mod.

Next up is an in between thermostat, I can not run a 170 with my 04 , but I might be able to get an in between according to a local racer, so ideally

• @Extinct Inline mod
• Hi Flow 180 Thermostat or a Hi Flow 175 thermostat (175 is about 79C)
• Aftermarket oil cooler if I can find a good place for it

The Hi-flow just allows more water to pass, they are more for hi flow pumps but as I often run at slow speeds an Hi rpm I figure I have nothing to lose but $50.00 by trying one.

 

Based on my personal testing I suspect even a 175 with throw a code. I used to be able to buy 175 degree thermostats for the inline housings but all the manufacturers have quit making that setting. When I could however, they would throw codes in mild weather. In warmer weather the thermostat goes right past the 170 and runs at 180 (Disco radiator/cooling system is only capable of maintaining a 100 degree differential). You might want to consider running either a 170 or no thermostat at all during the summer and putting in a 180 in the winter.

Working on an increased radiator capacity option for the Disco, we have missed the testing window in this hemisphere for this year but will be able to complete the fitment, brackets, and kit components over the winter. Will get my favorite mountain climbing beta tester signed up to test it next summer ;-)

 

40 oil makes sense, but I don't understand the preference for 15W oil. At operating temperature 5W or 10W oil has nearly the same viscosity as 15W oil.

 

@Discorama I live in Alabama and it seems to be a lot easier to find 15 or 20 weight oil. I agree that a 10w/40 might be the way to go.