Oil Consumption Question

[Don Z.]

In 1998 I bought my '66 and the previous owner used Havoline 10 W 40 for 10 years, so when I acquired the car I continued using the same. With all the posts and discussions regarding flat tappet engines and diesel oil, when changing my oil last fall I switched to Shell Rotella CJ-4. I wanted 10 W 40 but only 15 W 40 was available in this town unless you bought by the case.
Anyway, I have never used any oil, with the Havoline or this summer with the Rotella. That was up until this past weekend. I made a 150-160 mile interstate trip with speeds of 65-70 MPH.
After getting home and cleaning the car, I checked my oil and it was down 3/4 quart. I had checked it prior to leaving.
Why would I have oil consumption like this with this type of oil. I am just very curious of the loss using this type of oil.
Any thoughts appreciated. Thank You

[Dan H.]

Re: Oil Consumption Question

Hi Don, I use only the Shell Rotella 15-40 oil, go 2500 miles between oil changes and use NONE! It's not the oil, must be something else I believe.
Dan

[Paul H.]

Re: Oil Consumption Question

Don, I have been using Rotella 15W40 in my 61, 65 and 68 for many years and have experienced no oil use issues. I would not presume it's the oil causing your consumption issue. More than likely a ring or valve seal issue.

[Frank E.]

Re: Oil Consumption Question

Don, let it sit for a few days and then start it. Observe if you're blowing any blue smoke out the tail pipe. If so you may have some valve guide seals that are drying out. You can also take a look at the plugs for oil residue and PCV valve to see if it's rattling. You can also do a wet and dry compression test to check if you have a little ring wear causing blow-by at the higher rpms......

Just some thoughts.....

[Duke W.]

Re: Oil Consumption Question

I would not get exited about one data point. Many of us drive our vintage cars so little that we often can't get a good handle on oil consumption, and it's possible to use an incorrect technique or misread the dipstick.

Start a log and use a consistent measuring method.

1. The car must be on an absolutely level surface.

2. With the engine thoroughly warmed up (at least 20 minutes of around town driving) remove the dipstick after shutdown, wipe it clean and place it somewhere convenient.

3. Wait five minutes, insert the dipstick firmly to its seat, remove and read. The reason for waiting with the dipstick removed is to allow oil in the tube to drain. Otherwise it's easy to get a false reading.

Gas stations are a good time to do this. Remove the dipstick first thing and take the reading after you have finished fueling and paying. That's usually about five minutes, and most gas station pads are dead level.

Also note that reading the dipstick on a cold engine that has been sitting for a day or more will show higher readings than the above technique. Most of the hot oil up in the engine will drain down to the pan in a few minutes, but it will continue to drain down slowly when the car is not operating and the difference can be up to half a quart after sitting for several days (or weeks) compared to the reading you get with my recommended technique.

The 15W-40 viscosity range is okay for cold starts down to about 10 degees F, and few of us drive our vintage cars when it's that cold, so don't fret over the fact that CJ-4 is not avialable in the 10W-40 range. CJ-4 is available in 10W-30s, which is okay for cold starts down to 0 degrees F, but it's not commonly stocked at typical auto parts stores, especially in the southern tier states.

Duke

[Edward J.]

Re: Oil Consumption Question

To add what Duke says, If your car was never using any oil until the last oil change. it may just be that the oil level may not have been quite there at the full mark. sometimes in the process of pouring the oil from the container we tend to not quite let the container get empty so putting 5 or 6 qts (DEPENDING ON ENGINE) theres away something left in each container. just a thought,A long with Dukes comment checking after few minutes after shut down may end up being 3/4 of a quart.

Not to say that small block chevy valves are not a issue for problems concerning oil useage.

[Stuart F.]

Re: Oil Consumption Question

I trust you havn't had any spotting on your garage floor. Common for our old cars to dry out gaskets and seals from just sitting. I use the 15w 40 rotella as well and notice more consumption/leakage than when I use the 10w 30 rotella (L-76 w/ 46k). For one thing, it seems easier to slightly overfill the heavier oil and a bit harder to gauge the level on the stick. I used to always check the level before starting as part of my pre-start procedure and found my self topping up some. Then when I'd check again after shutdown, I'd find I was a little over filled. Normally, I only use the 10w 30 during the cooler months here in Florida (intend to change to it again soon), but probably won't change my routine until I run down on my shelf stock.

Stu Fox

[Don Z.]

Re: Oil Consumption Question

Thanks to all for the comments. I've not seen any blue smoke as was commented on. I do have a light tap on one of the front cylinders, but I've had that from when I bought the car.
Duke, I've never thought of it the way you put it and it make a lot of sense to me. I'll give it a try checking it that way.
I did a short run yesterday, approx. 60 miles round trip. Checked it after getting home and it was right on the mark.
Again, Thank You for the responses.

[Clem Z.]

Re: Oil Consumption Question

cool the dipstick by putting it in cold water to cool it off and the oil will "stick" better to a cold dipstick