Can a mechanic tell if the last oil used is mineral or synthetic from a dipstick
1994 Ford Thunderbird

Can a mechanic tell if the last oil used is mineral or synthetic from a dipstick

(1994 Ford Thunderbird)
On 8/27/2019, I specifically said to use 1 qt. of 20/50 & 4 qts. of 10/30 to change the oil. Have been using for the past 5-6 yrs. Car was blowing lots of smoke, then quit after using the formula above. Engine has over 250K miles, original engine. This last oil change blew a huge puff of smoke & continues to blow every so often. I want to add more oil, but concerned they put synthetic in & I use the oil mix, NOT synthetic.
Can one determine what type of oil has been used by looking at the dipstick? What should I do?
What seems to make the problem better or worse? after it heats up
How long have you had this problem? since 8/26/2019
Tags: ford, thunderbird
1 answer & 0 comments
Popular Answer
on October 01, 2019

The only thing I can think of is change the oil again using whatever combination you desire.

No way to determine what’s in the engine now other than an oil analysis - that seems extreme to me.
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on October 01, 2019

The only thing I can think of is change the oil again using whatever combination you desire.

No way to determine what’s in the engine now other than an oil analysis - that seems extreme to me.
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