[Tony_D]

I changed the oil in my 1966 GTO this month and decided to have it tested. The engine was rebuilt in 2004 and has 3315 miles since (389 -4, Auto). I changed the oil last 3 years ago and it has 141 miles on it.

I've been changing the oil every 3 years because I put so few miles on it and was wondering if I should continue this practice.

I tried to attach the report but it exceeds the limit for pdf and jpg files. Apparently the lab has data on 389 Pontiac engines because they compare my results to a 660 mile engine.

At the recommendation of my engine builder, I run Valvoline SAE 30 oil. I also add a 2 oz bottle of ZDDP MAXX at each oil change which is why the zinc and phosphorus numbers are high.

I am very happy with the results; no abnormal wear! Also, the TBN at 6.2 shows that there is life left in the oil at 3 years so I will continue my maintenance practice.

TBN = Total Base Number and is a measure of the alkaline base in the oil. Acids are generated by engine operation which attack the base reducing the life. A value of 3 or lower means it needs to be changed.

If someone can tell me how to reduce the size of the report I'll attach it.

[ZeGermanHam]

Glad to hear that your oil analysis came back good. You will learn more about it when you send in a follow-up sample after your next oil change, since they will then be able to compare the levels from one interval to the next.

As for uploading your report, convert the PDF to a JPEG (image file), then upload the JPEG. If the JPEG is still too large, you can try opening it in Microsoft Paint and then saving as a new file. Paint tends to reduce the file size of image files considerably. There are other more complex ways of reducing file size if you have imaging software, but that's a more involved discussion.

[Tony_D]

I think that worked; thanks for the tip!

[Tony_D]

Well, maybe this time...

[geeteeohguy]

Tony, I've been in the automotive repair industry for over 40 years now, and I have always done what you are currently doing with excellent results. I change my oil by mileage, not time. Sometimes it takes 4 or 5 years to put 3,000 miles on one of my old cars. Oil doesn't rot or 'go bad' sitting in an engine unless that engine is fired up for a few minutes and then shut off without the car being driven often. That will contaminate the oil with unburned off condensation, which forms acids. If you aren't going to drive the car, don't start it up. It takes about 5-10 miles of driving at operating temperature to burn off all the moisture.