In town, I typically carry 1 qt of oil in each vehicle, and a gallon of antifreeze in the Toyota.
Weekend trips I carry 3 qts of oil (never had to use any though)and a gallon of antifreeze in which ever vehicle is selected for the cruise.
The only times I carry extra fluids are:
- Washer fluid during a salty bizzard melt
- 1qt of oil during new car/engine break-in...and only if I need to take a trip that requires more than one tank of fuel.
- A long time ago I used to take a trunk full of bottled ethanol to Bloomington during Little 500, too.
Thankfully none of our current vehicles leak or burn any fluids so we don't carry any. However, I did once drive a 1961 Chevy Impala that leaked so bad that I had to carry several 2 1/2 gallon cans of the finest SA 30 oil you could purchase in 1971 . The engine finally seized on the way home from a most enjoyable night at the drive-in . I had filled the oil up only 70 miles previously when I got gas . It had a very leaky side pan gasket that my father refused to let me fix . Too bad because it really was a nice car.
I've always carried a litre of oil (currently a quart...it's a redline bottle). I've rarely used it, and usually then on a relative's car.
One car I carried 6 litres. I needed to.
And washer fluid.
And whatever fuel additive is running.
I don't have any vehicles that consume any oil/transmission fluid so I don't see any reason to.
I used to know a guy who kept a couple cases of cheap dino in the back of his old Ford Ranger. He had a rear seal leak and would have to put in a quart or two a day depending on how much he drove (yes, that was a quart or two a day). It leaked like sieve.
My vehicles don't use any fluids (except wiper fluid), but I carry a little oil, 50/50 coolant mix, wiper fluid, FP60 and paper funnels, and ATF/gear oil all the time anyway.
I also carry a tire gauge, a fire extinguisher, flares, refletive triangles, a headlamp, a blanket, two space blankets, duct tape, an emergency whistle, a first aid kit, a belt repair kit, a hose repair kit, drinking water and an Uno deck.
In winter I also carry chains, a snow brush, an ice scraper, a collapsible snow shovel and a can of de-icer.
Yes, I was a Boy Scout.