Should I switch from 10w30 to 5w20? Switch to High Mileage Oil?

Joined
May 29, 2015
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311
Location
Phoenix-ish, Arizona
My Crown Vic has 208,000 miles on it, about 50/50 highway and fast moving city traffic, but much of it in brutally hot Phoenix summer temps.

For the past four years I've been doing 12-month/10,000 mile OCIs with Kendall GT-1 Synthetic 10w30 and a Wix filter. Engine has no drips and only burns a cup-and-a-half of oil between changes. I think that's pretty great!

The last time I took my car into the shop for an oil change, they forgot to use my oil and filter that was in the trunk, and instead put Valvoline conventional 5w20 in it with a jobber filter. I didn't know this at first but I DID notice driving home that the engine felt "lighter" when accelerating. Noticeably easier acceleration. I liked how it felt!

It was only when I opened the trunk and found my oil still in there that I drove back to the shop and learned that they had filled it with 5w20. I would have kept the Valvoline in it but I didn't want to have to come back in a few months for another oil change. They re-did the oil change using my Kendall and filter. Good to go for another year.

But now that I need to buy some more oil, I'm wondering if I should switch to 5w20? Would that be asking for trouble in an older engine with seals this old? The oil cap says 5w20, but it's the same engine that was originally designed around 10w30. It can basically use either.

These cars are not picky about oil, but it is getting a bit long in the tooth. Some of my options at this point are to:

Keep using GT-1 Synthetic in 10w30. How's the new formula without Titanium?
Switch to GT-1 in 5w20. Engine works less hard but seals might develop drips?
Switch to a Valvoline 5w20 that can do longer OCIs. Same as above.
Switch to a High Mileage oil in 5w20. Might prevent drips?

What do you guys suggest?

Sorry for the length of this post, and thank you for your time.
 

pbm

Joined
Apr 19, 2004
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New York
I'd try Valvoline Maxlife Hi-Mileage 5w20 or Mobil 1 High Mileage 5w20 and keep an eye out for usage. You may pick up a little MPG improvement which we can all use with the current gas prices...
 
Joined
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I would try the 5w-20. I did and consumption stayed the same between OCI's (0) in my three vehicles. As you noticed, the engines run smoother, quieter and "lighter" with a small boost in MPG. OCI's are 5k miles and one year (or more on vehicles that don't get driven often. The 4Runner was changed to 5w-20 when I learned Toyota back spec'd it and that was at 270k miles.
 
Joined
May 12, 2017
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113
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California
My Crown Vic has 208,000 miles on it, about 50/50 highway and fast moving city traffic, but much of it in brutally hot Phoenix summer temps.

For the past four years I've been doing 12-month/10,000 mile OCIs with Kendall GT-1 Synthetic 10w30 and a Wix filter. Engine has no drips and only burns a cup-and-a-half of oil between changes. I think that's pretty great!

The last time I took my car into the shop for an oil change, they forgot to use my oil and filter that was in the trunk, and instead put Valvoline conventional 5w20 in it with a jobber filter. I didn't know this at first but I DID notice driving home that the engine felt "lighter" when accelerating. Noticeably easier acceleration. I liked how it felt!

It was only when I opened the trunk and found my oil still in there that I drove back to the shop and learned that they had filled it with 5w20. I would have kept the Valvoline in it but I didn't want to have to come back in a few months for another oil change. They re-did the oil change using my Kendall and filter. Good to go for another year.

But now that I need to buy some more oil, I'm wondering if I should switch to 5w20? Would that be asking for trouble in an older engine with seals this old? The oil cap says 5w20, but it's the same engine that was originally designed around 10w30. It can basically use either.

These cars are not picky about oil, but it is getting a bit long in the tooth. Some of my options at this point are to:

Keep using GT-1 Synthetic in 10w30. How's the new formula without Titanium?
Switch to GT-1 in 5w20. Engine works less hard but seals might develop drips?
Switch to a Valvoline 5w20 that can do longer OCIs. Same as above.
Switch to a High Mileage oil in 5w20. Might prevent drips?

What do you guys suggest?

Sorry for the length of this post, and thank you for your time.
For Phoenix area I would not change a thing. There is virtually no benefit to making any change with your temperatures. Stay with what you know and forget any changes.
 

shiny

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Joined
May 29, 2015
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Phoenix-ish, Arizona
Thanks, guys. It's not that I'm trying to eek out a fraction better MPG for fuel savings. It was just that the 5w20 seemed to make my engine work less hard. I was wondering if that would be of benefit for extending its life.
 
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Massachusetts
Thanks, guys. It's not that I'm trying to eek out a fraction better MPG for fuel savings. It was just that the 5w20 seemed to make my engine work less hard. I was wondering if that would be of benefit for extending its life.
If maximum engine life is the goal a thicker full synthetic is better, especially at those temps.
 
Joined
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For Phoenix area I would not change a thing. There is virtually no benefit to making any change with your temperatures. Stay with what you know and forget any changes.
Your engine doesn't care what the temperatures are in Phoenix. It does care about the coolant, radiator and thermostat temperature. The only time an engine struggles with temperature is during Winter before the coolant/oil warms to operating temp.. When I lived in Phoenix I was using the original M1 5w-20 in my 1958 Ford with the inline 300ci. Engine was fine (it liked the Winters there too).
 
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Crown Vics are great, when you take care of them. For 208k miles, keep doing what your doing.
 
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Location
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These cars are not picky about oil, but it is getting a bit long in the tooth. Some of my options at this point are to:

Keep using GT-1 Synthetic in 10w30. How's the new formula without Titanium?
Switch to GT-1 in 5w20. Engine works less hard but seals might develop drips?
Switch to a Valvoline 5w20 that can do longer OCIs. Same as above.
Switch to a High Mileage oil in 5w20. Might prevent drips?

What do you guys suggest?

Sorry for the length of this post, and thank you for your time.
Without question, use 10w30

A humans we look to do something different for the wrong reasons. You have over 200,000 miles on your vehicle and dont burn any oil.
 
Joined
May 17, 2009
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Way back in 2001, I I found my new 2001 Bullitt ran like it was pulling an Airstream trailer with 5W30 - the oil the Lincoln Dealer put in at my first OC - since they didnt have any of that new 5W20 "watery oil". I am not exaggerating. But since you don't have a new engine (200K+) , and we dont know the bearing health, I would stick with the 10w30. You are feeling the piston acceleration improve with the lighter oil where the pistons are scraping the oil off the bores at 40 MPH.

At this point I would start thinking about renewing the timing set. its a pain on this OHC, but its probably time.

My brother and niece just moved to AZ. The weather has been brutal since they moved; first it was weeks of 115+ temps,
then weeks of torrential rain. One storm blew his pool house off the foundation!

Really messed up weather these days!
 

shiny

Thread starter
Joined
May 29, 2015
Messages
311
Location
Phoenix-ish, Arizona
Way back in 2001, I I found my new 2001 Bullitt ran like it was pulling an Airstream trailer with 5W30 - the oil the Lincoln Dealer put in at my first OC - since they didnt have any of that new 5W20 "watery oil". I am not exaggerating. But since you don't have a new engine (200K+) , and we dont know the bearing health, I would stick with the 10w30. You are feeling the piston acceleration improve with the lighter oil where the pistons are scraping the oil off the bores at 40 MPH.

At this point I would start thinking about renewing the timing set. its a pain on this OHC, but its probably time.

My brother and niece just moved to AZ. The weather has been brutal since they moved; first it was weeks of 115+ temps,
then weeks of torrential rain. One storm blew his pool house off the foundation!

Really messed up weather these days!
Thank you, and thanks to everyone who replied.

I get what you're saying about the bearings. Probably not going to change the timing chain yet, if at all. My mechanic thinks it looks good, and the repair would cost more than the worth of the car.

Kendall GT-1 synthetic changed its formula. Compared to the titanium formula, the noteable changes I see with the new "LiquiTec" 10W30 is lower TBI (from 8 to 7), higher VI (from 153 to 166). On the good, it has higher HTHS. Will the 10W30 be too thick? Would you use it?

As for the weather, that is just typical Arizona monsoon season. We seldom get nice long, gentle rains. We get torrential storms that are over in 20 minutes leaving devastation in their wake. This has been the mildest summer anyone here can remember in years. We had one really hot week early on, then unusually cool temps (for us) and a lot of gentle rain (for us). Going into a hot week now, but that's par for the course.
 

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Joined
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Missouri
Thank you, and thanks to everyone who replied.

I get what you're saying about the bearings. Probably not going to change the timing chain yet, if at all. My mechanic thinks it looks good, and the repair would cost more than the worth of the car.

Kendall GT-1 synthetic changed its formula. Compared to the titanium formula, the noteable changes I see with the new "LiquiTec" 10W30 is lower TBI (from 8 to 7), higher VI (from 153 to 166). On the good, it has higher HTHS. Will the 10W30 be too thick? Would you use it?

As for the weather, that is just typical Arizona monsoon season. We seldom get nice long, gentle rains. We get torrential storms that are over in 20 minutes leaving devastation in their wake. This has been the mildest summer anyone here can remember in years. We had one really hot week early on, then unusually cool temps (for us) and a lot of gentle rain (for us). Going into a hot week now, but that's par for the course.
I would get a UOA done if you haven't recently to see how your engine is wearing. The lab will be able to flag if the elements correlating to timing chain wear are above average.

I wouldn't worry much about the Base Number decreasing in new oil, it seems that there have been some chemical advancements with API SP where a lower TBN with a new oil can keep that number longer.

If TBN is a big factor for you, I'd switch to 5w-30. There wouldn't be much difference at the temperatures you see.
 
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