I'm always frustrated with the odd setup needed to convert buildvraft oil into it's various temperature states.

If possible, I'd like to see integration with Mekanism and/or pneumaticraft's temperature manipulation mechanics and items.

I'm not familiar with either mekanism or pneumaticraft, so:

How does their temperature manipulation work? Do they take one cold fluid and heat it up to a different hot fluid? If they do, then what blocks do that?

https://youtu.be/zZ4diYRUZhs?t=180
I refer to Direwolf20's recent video where he shows how to make plastic with pnuematicraft using a vortex tube and a heat frame.

well, i'm unsure about what Border999 had in mind with this, maybe its just like the issue with MJ<->RF but here we talk about the same thing: heat, so maybe it will worth the effort.

Mekanism's heat is more like liquids and energy, you can create it with a machine that consumes something (boiler, resistive generator), you can transport it with pipes, and it is consumed on its respective machines (thermal evaporation chamber) but it decreases over time (heat dissipation)

Pneumaticraft's heat is a bit more complex (realistic), its not related to fluids but metal blocks (compressed iron), and AFAIK there is 1 machine that can move heat between others, the Vortex Tube, it moves heat from 1 side to another, but it was designed to use Compressed Iron Blocks, not liquids, so idk what would be the best compat implementation.
This is the machine: https://youtu.be/601eqGTbCCQ?t=676

Anyways, Mekanism has compat with Pneumaticraft so you just need to add compat with one of the mods, lets see what Border999 says.

(at least i think that a nice compat implementation for Pneumaticraft would be this:
-you put 2 BC tanks on each side of the Vortex Tube
-You add power to the Vortex Tube and it will change the temperature of the liquid inside the BC tank)

(another compat solution would be using Steam (and IC2Steam) to warm liquids from cool to hot, and then using IC2OverheatedSteam to warm liquids from hot to boiling (this would be a perfect moment to talk about that issue with IC2 Coolant))

I refer to Direwolf20's recent video where he shows how to make plastic with pnuematicraft using a vortex tube and a heat frame.

you mean using the refinery to produce Buildcraft's Fuels? just use Crafttweaker and add the recipes, but i highly recommend you to build a refinery plant with Buildcraft, it is pretty cool

Just wanted to throw a suggestion. Heat Frame, it seems logical to have stuff like the heat syncs to be able to cool down items and the heat frame to manipulate teperature