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Low gas mileage after long overdue synthetic oil change
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benhorton2
New User
Aug 2, 2013, 6:23 AM
Post #1 of 4
(1290 views)
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Low gas mileage after long overdue synthetic oil change
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I recently had my friend's 2003 Volkswagen Jetta wagon into the shop, which had gone 26,000 miles since the last oil change, the current mileage was 98000. They recommended the full synthetic oil and filter change for high mileage vehicles. Now she tells me her gas mileage has dropped significantly, a 100 mile drive cost her 25 in gas. I have read that synthetic oil works great if the car is properly maintained, but that the additives in the synthetic oil can break down deposits plugging worn seals. The car had been burning oil slightly before this oil change. The shop also used 5W-30 instead of the recommended 5W-40, but i don't think that would cause such a significant drop in gas mileage, although the thinner oil would seem to have more potential to leak. I figure the oil filter may also be getting clogged due to the broken down sludge build up. Would poor mileage be a symptom of either of these? Or is it possible that the engine needs to adjust to the new oil? Should it be driven, and will a switch back to conventional oil help, and if there is a like are there any additives i could use to safely help a leak? And if something is wrong, can I make the shop at least give me a new oil change or pay for the repair, as they were informed how long it had been since the last service, and they recommended this oil.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 2, 2013, 6:32 AM
Post #2 of 4
(1285 views)
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Re: Low gas mileage after long overdue synthetic oil change
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I don't see the oil change having any bearing on the fuel mileage unless the left something unplugged or disconnected in the process.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Aug 2, 2013, 8:27 AM
Post #3 of 4
(1270 views)
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Re: Low gas mileage after long overdue synthetic oil change
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Check engine light on?
100 miles costs 25 dollars?
What is the actual fuel mileage? Is this highway or city driving? Which engine?
Why did she drive so long without changing the oil? When you state it burns oil, how much?
How was it determined the engine was sludged up?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Aug 2, 2013, 8:28 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 3, 2013, 8:26 AM
Post #4 of 4
(1256 views)
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Re: Low gas mileage after long overdue synthetic oil change
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Quote ">>And if something is wrong, can I make the shop at least give me a new oil change or pay for the repair<<"
#1. Synthetic oil did not cause a problem. Driving 26,000 miles on any oil is a problem and now it's not even confirmed by saying it only went so far by the dollar means little just yet. Real MPG as DS asked.
Sludge? Who knows if it did or didn't yet? I'm not sure there's enough here to say there's a problem at all and already with that abuse you want a shop to pay for the repair and don't even know yet if it needs one.
I can just see Judge Judy with that one - HA,
T
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