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Greg, Shop Owner
Category: UK Car
Satisfied Customers: 7115
Experience:  17 years Shop Owner /Technician. 27 years experience,
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2003 F350 6L diesell.Since oil and filter change -

Customer Question

2003 F350 6L diesell.Since oil and filter change - semi-synthetic oil in error now changed to correct Motorcraft 15W40 oil - slow to start and misfiring. Mechanic reports low compression cylinder 7 and wonders if there's an internal engine problem
JA: When was your last oil change?
Customer: Two weeks ago' three days after wrong oil.
JA: Are you fixing your F350 yourself? What have you tried so far?
Customer: It's at the garage - I'm considering having injector 7 replaced and see where that leaves us.
JA: Anything else you want the mechanic to know before I connect you?
Customer: The problem emerged straight after the wrong oil and wasn't slow to start or misfire before that - I can't understand how a change of oil could damage the compression in one cylinder
Submitted: 9 months ago.
Category: UK Car
Expert:  Greg replied 9 months ago.

Hi, I'm Greg (Indy-Tech).
Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP.
Rgds Greg.

Expert:  Greg replied 9 months ago.

Have the shop do a injector test ,this is where the injectors can be singularly switched off .

this will let you know which one is weak .then have them removed and tested .

A good diesel shop should be able to recondition the injectors ,save you having to reprogram new injectors .

If compression is low on that one cylinder then replacing the injector is not going to change anything .

The low compression issue will have to be checked first .this could be piston rings,valves .or possible head gasket .

Need further assistance with this issue then please get back to me with the reply box below .
After rating there is no further cost for any other question relating this issue .
Kind regards Greg