Mixing oil types (5w-20 mixed with 10w-30)

Well this problem has probably resolved it self as the OP hasn't ben back and he was traveling on 11/26/15.
The take away from this (that a bunch apparently missed)He was going to take a new to him coach on a 4-5 hour trip. The oil when he picked it up was at the low level. He doesn't know what the consumption/leakage rate is for this coach. I still maintain the best practice is to fill it to the full level and check it at several points on the trip. He needs to keep an close eye on the level until he develops a history of the consumption.
Bill

I understand the 5W-20 spec is primarily for increased fuel economy. If I were down by one quart and was driving 4 hours to my next oil change, I would add a quart of that higher viscosity oil. If for no other reason, the extra quart will help to remove more contaminants when drained.

Engine lubricating oils can be mixed without problem. A 10W-30 is really little different from a 5W-20 with respect to lubrication at normal operating temperatures.

I'm not sure about "top it off" since the package size is usually a quart, and the difference between the "low" or "min" mark and the "full" or "max" mark on a dipstick is usually a quart. I carry oil, check levels daily when moving, but add oil only when it drops below the "low" mark (which has happened maybe twice in the past 20 years of driving). We've come a long way from the "add a quart every 600 miles" days.

Harvey51 wrote:
The same question applies to engine thermostats. In the old days people would install a higher temperature thermostat to make the cabin heater work better. Now it is just too much trouble to change them. We put cardboard in front of the radiator - often forgetting it and overheating the engine in the spring. There has to be a better way.

Your thermostat is probably stuck open a bit.
Actually they are designed to fail open but no-one notices that... just the stuck closed failures.
Replace with OEM rating.

Yes things have changed in the last 50 years. The oil today is not the oil your grandfather used. In the cold north I would run the 0-20 in the Ford. People use to run 160 thermostats in the summer and 180 in the winter. Now your Ford runs a 190 degree year round. It will give plenty of heat in the winter.
Bill

Anyone know why Ford specifies 5W20 rather than the far more common 5W30 for the E350 engine? I think the 20 and 30 refer to thick it gets when hot.

Here in the north people have often used a grade lighter in winter, as in 20 instead of 30 in the years before multigrade motor oil, and now 0W30 instead of 5W30. They say it is noticeably easier to start the engine at low temperatures. It seems odd to specify the same viscosity regardless of climate.

The same question applies to engine thermostats. In the old days people would install a higher temperature thermostat to make the cabin heater work better. Now it is just too much trouble to change them. We put cardboard in front of the radiator - often forgetting it and overheating the engine in the spring. There has to be a better way.

If you read the bottle you will see that they are "compatible". If you research you will find that this word was added when synthetic oil cme to be common. It means that all oils, within the same spec can be mixed. It will vary the weight, so if to 6 qts of 5W20 you add 1qt of 10W30 you will end up with 6W22 or close. This was explained to me by one of the engineers of exxon mobile when they were making the pitch to use Mobil 1 in the Dodge Viper as the factory and recommended oil(I used to work at Chrysler at the time)
I have been doing it for 15 years, never had an issue with it. Any weight, synthetic, blend or regular old dyno, as long as the weight is within 10-20%.

My 5.4 has run the last 100,000 miles on 5w30 instead of 5w20. Mix them? No issues.

I would far rather have slightly wrong viscosity to being a quart+ low on oil any day.

Threads like this always amaze me. Most posters are correct, but there are still a few that take the time to post an opinion, rather than stick with the facts. The high and low level indicators define the operating range. These values were carefully calculated by the designers of the engine. They expect that you will monitor the oil level to determine that it is constantly in the operating range, and add a quart when the level is even with, or below the "low" indicator. This silliness of trickling a few ounces in, or even worse "just add a quart and go", is not how it works. Adding a few ounces of oil is no different than waxing your rig since you just know that it improves the MPGs. If that's how you chose to waste your time, carry on, but it's not something that matters in the least.

Is the vehicle sitting level? Has the engine sat for a few minutes to allow all the oil to return to the pan? Is the level is the operating range? If the answer to all three is yes, you're good to go.

We had an '88 with the Ford 460 engine, when you changed the engine oil and filter it took 6-1/2 qt. I changed the oil and filter myself. After the first few times I got tired of splitting quarts of oil, so I only put 6 gt. when changing, then if it dropped to the add mark I added a whole gt.
We had that mh for 14 years. Drove it for maybe 80,000 miles.

Dusty