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Don, ASE Certified Technician
Category: Car
Satisfied Customers: 1668
Experience:  30 years journeyman experience on classic cars
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Jeep/Ford Wrangler SE/Escort/E150/Focus Dear Experts, So

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Dear Experts,

So far this format as been very helpful- with my vehicle repair.

I have gotten some uncertain info from retailers and auto parts people regarding the use of motor oil. Many seem to have their 'favorite' oils.
Can you advise with info as to use of synthetic oils in these vehicles?
I have four vehicles:

'01 Focus w/107K miles- regular 5w20 Motorcraft semisyn
'01 E150 w/115K miles - regular 5w20 Motorcraft semisyn
'93 Escort w/64K miles 5w30 Valvoline semisyn/high mileage (because of time element)
'97 Jeep Wrangler w/156K miles 10w30 Valvoline full synthetic high mileage

My ?s-
Can I revert back to conventional oil at any time? (after use of full or semi syn oil)

I have some conventional Valvoline oil - can I mix that with an equal amount of Valvoline full synthetic of the same weight (I don't want to waste it) essentially 'blending' oil?

Is the use of high mileage oil advisable in all of these vehicles?

Use of this site for 'real' info will further prove its worthiness- I appreciate your efforts.

hi ther my name is don
i will try to help you on this

most people have favorite compamies that they like to use some because of warrenty and name or thier father used it and so they continued on

the basic oils must meet certain standards set out by goverment regulations

most of the problems come when a car has had regular none synthetic oil for many miles and because of reputation of synthetic oil they start using it in their cars and things start happening like oil pressure , oil leaks and so on

fully synthetic oil is a high content of detergent i it and it cleans as it lubricates so that the soot and carbon that has developed from using a regular grade oil is essentiially washed away from seals beqarings and so on

if you are using a fully synthetic oil you can revert back to regular oil but you will notice a reduction in fuel milage

a semi-synthetic oil contains some of both features of regular grade and synthetic blend giving you better lubrication ,and not high in detergent .

if you are using regular grade oil you can switch to a semi-synthetic blend with no problem .

i would not however mix the two valvolene,s together

you could however with the semi-synthetic

walmart oil for an example is made from the same blend (at the same time as valvolene and so on and just labeled for them .

i hope this answers ypour question
Don and 9 other Car Specialists are ready to help you
hi there thanks for the accept it was my pleasure to assist you
have a great day