4cyl Oil Amount?

These are the last 4 oil changes I've done. Solid line is 5qt off the shelf. Dotted line is how much oil came out of my truck. I always fill with exactly 5.5qt, and OEM filter.
I know that the dipstick is almost useless on the 4cyl and I know that there is some disagreement on oil volume. Owners manual says 6.1qt (with filter) - could that be for a dry engine? Could the heads and balance shafts be holding .5qt+ each time I change the oil?

Interval is 3000-5000mi. 90% highway miles. Truck has just about 40k miles on it.
What does everyone think? Am I underfilling/overfilling?
Thanks in advance!

 

I think you are over thinking this. If you put oil in engine near published spec and it shows up on the dip stick approximately between the high and low marks, crack a beer and throw a ball for your dog.

I also don’t think dip sticks vary much across engines or decades. They are not precise instruments. The popularity of low viscosity oil these days probably reduces their precision even more.

If precise control of oil volume was critical, manufacturers would provide more precise measurement devices.

What’s more important than oil volume is oil pressure. Because oil is incompressible, the theoretical minimum oil volume is equal to the volume of the bearing, valve, etc interspaciings, and the oil galleries (oil tubes in the engine). Anything volume above that is just an engineering safety factor assuming there is not an extreme amount of oil volume.

There is a good reason automobiles have an oil pressure warning light but not an oil level warning light

Oh shit. I might be the one overthinking this.

 

^About that... (V6 only)



Since modern engines rely very much on oil for cooling, the oil volume is related to heat capacity. Plus the oil level has to be sufficiently high to avoid staving the pickup tube on inclines and in high-g maneuvers.

 

And I thought that I was anal retentive...
I must admit that I don't keep track of how much oil comes out of my crank case. (I do for the trans dump-and-fill though.) I put in 6 quarts of oil with a new filter every 4K to 5K miles. I do use the YZZD3 filter, which is slightly larger than the one Toyota specifies. I check the oil level every month or two, and I've never seen it drop. It reads up close to the Full bump (as near as i can tell). I guess I'm not that worried about how much comes out.

 

- What was your tire pressure averaging between OCI?
- What was the tire pressure during the oil change process?
- What was the average air temperature between Oil changes?
- did the air temperature fluctuate more than 15 degrees Fahrenheit at any time between OCI?
- Would you say your truck spent more time in the sun or in the shade between OCI?
- Any issues with the paint?
- How was the air flow through you air filter during this time?

If you answered yes or no to any of these questions it is quite possible you underfilled the oil by .023 mL and you may want to trade it in for an electric vehicle before you are denied warranty work by Toyota.

 

I don’t think you need to worry. All the previous ribbing aside, just keep doing oil changes.

Some will spout off about brand A being better than brand B and my grandfather said brand C sucked.

The most important thing is to change it regularly.

As far as the difference, don’t worry about it. I did an oil change in Callao, Peru. Early morning, tired, didn’t pay attention. Had the bottles of oil ready to go.

Made the mistake of going the wrong way with litre to qt conversion. Put in 6.2l which is around 6.6 qts. That was around 91k miles.

I’m over 180k now and all is well. That oil change was 10W30 dino oil as that’s all I could find around the port that early in the morning.

 

Yes, I know that I am over analyzing this way too much. I am driving A LOT for work right now and averaging oil changes every 5 weeks. I also have a lot of time on my hands and sometimes I just get bored and change the oil... or diff fluid... or detail the engine bay... I like projects. This thread made me feel better, thanks for the input everyone.