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#4660465 - 02/08/18 10:10 PM How many months can a synthetic oil last
BrianApp Offline

Registered: 06/22/16
Posts: 8
Loc: MI
How long, calendar wise, can a synthetic motor oil last in a car. I can go years in the 7,000 MI recommend interval but I thought I remembered that oil should be changed every six months regardless of the miles. That may have been talking about conventional oil though. I took it to the dealership but they said it wasn't due. With $20 oil changes for life they are motivated to keep the changes to a minimum. They don't care if the engine life is reduced but losing money on oil changes is not something they want to do.

#4660481 - 02/08/18 10:30 PM Re: How many months can a synthetic oil last [Re: BrianApp]
JustN89 Offline

Registered: 06/27/17
Posts: 300
Loc: DFW
Depends on too many factors to give a one-size-fits-all answer. While it's generally accepted that a quality synthetic can easily surpass the 12 month mark, the only way to know how long the oil will hold up in your particular engine is to get a UOA done.

#4660491 - 02/08/18 10:46 PM Re: How many months can a synthetic oil last [Re: BrianApp]
Reddy45 Online   shocked

Registered: 08/15/08
Posts: 2551
Loc: USA
Not that it represents anything, but I swear someone posted a UOA here of an old truck that hadn't had its oil changed in 2 years and the TBN was still pretty good.
2015 Toyota Tacoma V6 4X4

#4660493 - 02/08/18 10:49 PM Re: How many months can a synthetic oil last [Re: Reddy45]
bbhero Online   content

Registered: 03/20/15
Posts: 4200
Loc: Virginia
Great day... But I think you are right about that... It was like 2 yrs plus and that oil was still good.
Nissan Altima 3.5 Coupe
Federated Auto Full Synthetic 5w30 Hastings LF 240
"Treat your family like your friends and treat your friends like your family."

#4660495 - 02/08/18 10:51 PM Re: How many months can a synthetic oil last [Re: BrianApp]
Johnny2Bad Offline

Registered: 05/20/13
Posts: 1607
Loc: Saskatchewan, Canada
I give up. How many?
'57 FL Straight 50 wt
'90 Miata 1.8L w/Rotrex Supercharger [Mobil1 0W-40]
'96 Ram 1500 [3.7L Mobil1 0W-20 / 1L 15W-50]
'01 PT Cruiser [Mobil1 0W-40]

#4660496 - 02/08/18 10:51 PM Re: How many months can a synthetic oil last [Re: BrianApp]
Dyusik Offline

Registered: 09/26/14
Posts: 1752
Loc: US-WA
There was a report with dino hdeo that was looking fresh after many years. 7? Can't remember.
95 Cherokee 190K RT6 5W40,Denso
07 IS250 93K FB ?w??,FULL
04 YZF-R1 18K DELO 15w40,FU
99 HD XL1200S 18K 76 20w50,NAPAG
14 RX450h 28k M1 0w20,Denso

#4660510 - 02/08/18 11:15 PM Re: How many months can a synthetic oil last [Re: BrianApp]
FermeLaPorte Offline

Registered: 07/25/17
Posts: 375
Loc: Texas (south)
7,000 thousand is the most if you want to keep your vehicle for a long time.
Always Mobil 1
2014 1.6L Nissan Versa Sedan, 5 spd, 5k OCI.
2011 3.5L Chevrolet Impala, Automatic, 5k OCI.

#4660512 - 02/08/18 11:23 PM Re: How many months can a synthetic oil last [Re: FermeLaPorte]
CONMCK Offline

Registered: 05/09/04
Posts: 150
Loc: alberta
Good question. My 2005 motorhome with the ford V-10 gets an oil change every 2 years. Mind you the oil usually only has approx 3000 miles in those 2 years. That's using mobil 1 5w-30 full synthetic oil.

Edited by CONMCK (02/08/18 11:24 PM)

#4660513 - 02/08/18 11:24 PM Re: How many months can a synthetic oil last [Re: BrianApp]
Linctex Offline

Registered: 12/31/16
Posts: 5233
Loc: Waco, TX
There's a member on here that's got 5 years on Mobil 1.
UOA sample says it's still good.

My 1943 Farmall H has had the same 15W-40 oil in it for around 20 years now. The thing runs perfectly. The Ford industrial engine in my wood chipper has oil that's even older than that, But it only gets used an hour every couple years. (This is all plain "dino" oil, BTW)

It's been proven on here many times - calendar date on oil really doesn't matter.
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

#4660524 - 02/09/18 12:25 AM Re: How many months can a synthetic oil last [Re: BrianApp]
Nick1994 Offline

Registered: 02/19/13
Posts: 9639
Loc: Phoenix, AZ
A lot of months
2015 Hyundai Sonata 2.4L 74k PU 5w30 & OEM
2000 Toyota Camry 2.2L 227k M1 AFE 0w30 & Wix
1996 Jeep Cherokee 4.0L 145k M1 HM 10w40 & Fram Ultra

#4660527 - 02/09/18 12:37 AM Re: How many months can a synthetic oil last [Re: BrianApp]
Ducked Online   content

Registered: 10/25/12
Posts: 3845
Loc: Taiwan
You say regardless of miles. That has to include 0 miles, so it then becomes almost equivalent to the oil shelf life question, except that an engine isn't normally a nominally sealed container.

Valid answers to the shelf-life question are mostly expressed in terms of geological time, or infinity.


#4660531 - 02/09/18 12:49 AM Re: How many months can a synthetic oil last [Re: BrianApp]
daves87rs Offline

Registered: 02/23/09
Posts: 16790
Loc: Michigan
Well, my Cavalier is sitting at almost 2 years on it's QSUD change.....engine is still doing just fine....
Coming together is a beginning; keeping together is progress; working together is success.

Henry Ford

#4660562 - 02/09/18 04:39 AM Re: How many months can a synthetic oil last [Re: BrianApp]
Dave9 Offline

Registered: 08/28/17
Posts: 138
Loc: Cincinnati, USA
It depends upon the conditions under which you put on the miles you do. Suppose every time you drive it, you only go a couple miles. That is not long enough to warm up the engine, have it run lean, and have the oil heat up to cook off moisture. This is even more true in a Michigan winter where you might have to drive quite a while to get the oil up to temperature.

50 trips in this state is much harder on oil than 1, 50 mile trip. It also means starting the engine an additional 49 times, supposedly when engine wear most often occurs and where do these wear particles end up? Either as deformation or more often in the oil.

No it does not need changed every 6 months in "most" cases, but if you were to drive a mile a day every day, "maybe" it needs changed on a yearly schedule.

More to the point, if I were you with low miles, what I would do is "sneak" in an additional oil change between each of the dealer free 7K oil changes. Maybe use the same filter brand so they don't catch on (or don't, that shouldn't really change anything). Don't reset the oil change indicator if the vehicle is so equipped.

It may not be the perfect interval but it seems to make the most sense and still take advantage of the free oil changes.

Edited by Dave9 (02/09/18 04:44 AM)

#4660565 - 02/09/18 04:49 AM Re: How many months can a synthetic oil last [Re: BrianApp]
ZZman Offline

Registered: 03/17/08
Posts: 5376
Loc: Michigan
The standard is 12 months from what I have seen.
2003 Mercury Grand Marquis. Rotella T6 Multi-Vehicle oil
2008 Sebring Hardtop convertible. Rotella T6 Multi-Vehicle oil
2006 Kawasaki Vulcan 900 LT

#4660570 - 02/09/18 05:00 AM Re: How many months can a synthetic oil last [Re: BrianApp]
otis24 Offline

Registered: 10/30/05
Posts: 1648
Loc: South Dakota
Depends on driving habits. I go strictly by Oil Life Monitor. The last two times, I have gone 10k miles (about 6 months) each time. But that included a 3k mile round trip in each case. I think there is a big tendency to focus on TBN while ignoring TAN. In general, my vehicle is a short tripper, but the OLM factors that in. I do not have any big trips planned before the summer so it will be interesting to see if the OLM trips sooner this go around.
1991 Chevrolet K1500 (4.3, 4x4, 86k miles)

2016 Dodge Grand Caravan
(3.6 V6) 46500 miles

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