The oiler fix is to have military and population use some baseline oil each turn. Instead of land tax. Probably even better if only jets and land so it penalizes the heavy jet countries more if oil price spikes.
Just convert military expense and land tax amount to oil at $80 per barrel. E.g. where you had $80000 in jet expenses now you no longer lose cash instead 1000 barrels per turn.
The problem there is the barrel price assumption. If you take last reset the per turn costs are already higher fpr non oilers because oil was $100. The equilibrium point for a farmer at 220% @$36 bushels is $153 oil. The rquilibrium point for an oiler and casher is roughly $220 per barrel but I dont remember. Idealy changes would want to bring oiker to a consistently competative point.... thus somewhere between $153 and 275 per barrel which, under your suggestion would double or even triple per turn expenses.
You also realise trying to nerf the strength of an all-jetter will also reduce the capacity of countries to jet up and retal which means a big fat dominating commie will be almost unstoppable. At this point the best way to stop a jetter is to kill it (something I am against on solo servers). The way DRs work for special attacks need to be looked at because a failed KR or an AB run on a jetter with enough stock is a license to farm the sever with no consequences aside from potentially being killed. The other thing is that whatever change is made to try and nerf jetter will have a workaround within the bounds of the game and hurt players who need to run heavy jets to retal. By nerfing jetter, you are by extension and consequence nerfing other strats that take longer to get going.