The most common and most likely answer to this crossword clue is the 6 letter word CASTOR
I've seen this crossword clue in The Daily Telegraph
C
A
S
T
O
R
Buddy explains!
The straight part
We know that "Kind of oil/wheel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case kind of oil/wheel = castor.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CASTOR mean?
CASTOR noun- A hat made from the fur of the beaver.
- A heavy quality of broadcloth for overcoats.
- Castoreum (bitter exudate of mature beavers).
- Any of various nymphalid butterflies of the genus Ariadne, of Africa and Asia.
- A variety of petalite found in Elba.
- Someone or something that casts
- A wheeled assembly attached to a larger object at its base to facilitate rolling. A caster usually consists of a wheel (which may be plastic, a hard elastomer, or metal), an axle, a mounting provision (usually a stem, flange, or plate), and sometimes a swivel (which allows the caster to rotate for steering).
- A shaker with a perforated top for sprinkling condiments such as sugar, salt, pepper, etc.
- A stand to hold a set of shakers or cruets.
- The angle of the axis around which a car's front wheels rotate when the steering wheel is turned, with a vertical axis being defined as zero caster.