Yup, I had that experience myself where even in neutral, there was enough gear oil viscosity to move the car or stall the cold-started engine, when you let out the clutch. I also had it when it was almost impossible to move the shifter out of reverse gear (for those of you who do not know about manual transmissions, that it the gear you put it in to park the vehicle so it does not roll or move when you turn off the engine), the transmission gear oil was so thick like cold molasses. I wised up, and like you will be doing, changed over to 75W-90 gear oil.
I also had a bad experience with a batch of Quaker State motor oil that the winter viscosity additives was not blending into the oil. This was I think in about 1979 or `80 in some 10W-40 we used in all our family vehicles. Needless to say , NONE of the vehicles that sat outside in a cold Wisconsin January would even turn over, even with a jumper cables to boost the battery starting energy draw. I had to drain the oil out OUTSIDE, and when I removed the oil pan drain plug, it would not even flow!! It was like thin grease, literally. I put a screw driver in the drain hole, thinking it was just "frozen" or congealed at the hole, but no, it was the entire oil in the pan. Luckily I had a 150,000 BTU fuel-oil space heater (AKA Reddy Heater) at that time, so I placed it under the oil pan, heated up the oil enough so that I could start the vehicle, allow the engine heat to get the oil warm, and then change it along with the filter. I had THREE vehicles to do that it. Getting warm oil on your bare hands and fingers in -10°F weather was a recipe for instant frostbite and it was a throbbing-hurt like someone hit your fingers with a hammer when I went inside to warm up my hands. I repeated this THREE times that day, and yes, it was a cold, painful ordeal, not to mention the expense of 15 quarts of oil and 3 oil filters. I learned later that Quaker State suffered a class-action law suite filed by dealers because of this and replaced some engines, not to mention covering the cost of oil changes. I got nothing out of this financially from Quaker State, and my family still continued to use their oil for many years. I eventually switched over to Mobil 1 synthetic oil when it became more popular (like 1981 or 82) and never went back to conventional oils, even with the almost double-the-price over conventional motor oils. Is it worth it??? It is when your vehicle sits outside overnight like at work when it`s -25°F and it starts without drama or a lot of cold-engine noises.
