Farm Equipment - D 15 engine oil

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D 15 engine oil

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=208699
Printed Date: 29 Oct 2025 at 7:00am
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Topic: D 15 engine oil

Posted By: ACinSC
Subject: D 15 engine oil
Date Posted: 28 Oct 2025 at 5:33pm

Another dumb question, maybe. When I check the oil with a cold engine it's a touch low. After engine warms up oil level is on the line. Seems it should be the other way around to me. Thanks for any insight

Replies:

Posted By: steve(ill)
Date Posted: 28 Oct 2025 at 5:42pm

Google...

Yes, oil expands when it gets hot, a phenomenon known as https://www.google.com/search?q=thermal+expansion&oq=does+oil+expand+when+hot&gs_lcrp=EgZjaHJvbWUyCQgAEEUYORiABDIICAEQABgWGB4yCAgCEAAYFhgeMggIAxAAGBYYHjIICAQQABgWGB4yCAgFEAAYFhgeMggIBhAAGBYYHjIICAcQABgWGB4yCAgIEAAYFhgeMggICRAAGBYYHtIBCDUyOTNqMGo0qAIDsAIB8QUYyd47UkDKZw&sourceid=chrome&ie=UTF-8&ved=2ahUKEwisgP_N-8eQAxVjkokEHYf6LZsQgK4QegYIAQgAEAQ" rel="nofollow - thermal expansion . This is why it's important to check engine oil levels after the engine has been running for a few minutes and then has been allowed to sit for a few minutes to drain back into the oil pan, as checking it when cold can lead to overfilling if it's topped off to the "full" mark

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Like them all, but love the "B"s.

Posted By: SteveM C/IL
Date Posted: 28 Oct 2025 at 8:45pm

Steve,is what you say in the manual? Never heard of warming a little then setting to check oil. Can't imagine full cold could grow enough hot to matter.

Posted By: steve(ill)
Date Posted: 28 Oct 2025 at 9:30pm

i dont know about manual.. this is just a GENERIC comments about oil expansion due to heat... It can happen... E J just wanted an explaination of WHY the level changed with temp... I normally check oil level cold and call it good..

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Like them all, but love the "B"s.

Posted By: ACinSC
Date Posted: 29 Oct 2025 at 4:49am

Thanks Steve I didn't think about oil expansion. Makes sense. Guess if I add a little oil to get the level on the full line it wouldn't hurt anything?