Thank you for all your tips. This weekend I replaced the flame trap element (which was clear) and the O ring in both the flame trap housing and the oil filler cap. I wiped the oil filler spout totally clean. After having completed this, I drove the car and didn't smell much. But the smell returned after the next couple of drives. I checked around the oil filler neck and didn't find any evidence of oil. I was not able to get under the plastic spark plug cover because the final screw head stripped as I tried to get it off (a project for another day). Any other possible sources of the smell of oil burning when going uphill (seems to only happen when traveling at highway speeds, not at <40mph)? There is no leak, just a small seaping when under load (i.e., no spots under car).