Is synthetic worth it for older cars(88' Suburban)

[JasonTL]

So, I've got an 88' GMC Suburban that had previously been sitting dormant for two years. It runs good, but I haven't changed the oil yet and I don't know when it was last changed.
It's a 5.7L 350 with 207k miles.
My driving style is easy and most trips are short (10-30 miles) with back-road highways until I reach town. I will haul a light trailer occasionally. MPG is always nice but I know I'll never break any records on this vehicle.

I've read that synthetic can give better MPG, but not always. On some things I've read that synthetic can actually decrease MPG and efficiency in older cars.
I also know that synthetic costs about twice as much but usually lasts twice as long.

I'm wondering, is it worth using synthetic, or going with a mix, or sticking with normal?

What are y'alls thoughts? On Synthetic? On Normal?
I have no preconceived ideas about this and will use whichever seems to be best suited.

 

[147_Grain]

Probably not; stick with a dino-based oil and shorten your OCI.

Synthetic oils tend to have strong detergent packages that clean very well. (Some dino's do too).

Occasionally in a well-worn engine, fresh oil can remove some of the false seals (sludge) that are masking a weak area which normally would be leaking. This can cause an oil leak on a neglected engine.

 

[RowdyYates]

No. I would use a High Mileage Oil.

 

[LeakySeals]

I would try a full synthetic in that engine to see how it performs. 2 that come to mind are T6 5w40 and M1 HM 5w30/10w40.

 

[JT1]

My caprice 254k mi,gets synthetic. Mileage difference is not noticeable. I do it because I tend to extend the oil changes and I'm more comfortable with the better ad packs offered in synthetics.

 

[ottotheclown]

Put card board under motor after you do. Might prove a good idea. How did the car get old? would be a question I would ask myself.

 

[JasonTL]

@Otto, Good idea about the cardboard. I meant to do that before.
My Dad bought the car in 02 I think from a guy down the street. That owner had used it to pull an airstream cross-country I think.
Dad used it as a daily driver on a 13 mile city commute to work 5 days a week until 09 I think. Hmm, come to think of it the car may have actually sat dormant for 3 years before I started doing anything with it.

I don't know how the previous owner treated it nor if he was the first owner, sadly that leaves the first 14 years unknown. I know Dad had the tranny rebuilt but the engine is original. I don't think he was as zealous with oil changes as everyone here is. TBH he usually only does anything to his cars when they get too undriveable for him*. Only reason he stopped using this car was because it had an oil leak and messed up exhaust and he was able to get another identical Chevy Burb that didn't have any problems.

I've since had the exhaust redone and oil leak fixed. I don't think it's still leaking oil but I need to put cardboard down like you suggested to make sure.

I wonder if running synthetic once to try to clean it would be good, or not because it could open up leaks somewhere? Would this actually create leaks or just show me weak spots I'll need to deal with eventually anyways?

Thanks guys, please keep the suggestions and thoughts coming.

*Funny thing is for the most part this car is actually in better condition than his current one.

 

[Clevy]

Originally Posted By: LeakySeals
I would try a full synthetic in that engine to see how it performs. 2 that come to mind are T6 5w40 and M1 HM 5w30/10w40.


And neither are. Funny

Anyways OP. unless you can get them on sale I wouldn't bother with a syn. The potential des exist that leaks may develop although it is less common now.
PYB,defy,max life,whichever you can find cheapest and change at 5000 miles unless there is a fuel dilution issue,then change it sooner if there is one.

 

[LeakySeals]

Originally Posted By: Clevy
Originally Posted By: LeakySeals
I would try a full synthetic in that engine to see how it performs. 2 that come to mind are T6 5w40 and M1 HM 5w30/10w40.


And neither are. Funny

Anyways OP. unless you can get them on sale I wouldn't bother with a syn. The potential des exist that leaks may develop although it is less common now.
PYB,defy,max life,whichever you can find cheapest and change at 5000 miles unless there is a fuel dilution issue,then change it sooner if there is one.


And neither are what???

 

[Smokescreen]

Yep run a decent dino and call it a day. This engine will never ever increase mpgs from changing to synthetic. I know, I have tried. It's just not worth it. You could run 5w30, 5w40, 10w30, 10w40, 15w40 it wouldn't matter it will get the same fuel economy. As long as you keep changing the oil regularly it will keep running.

 

[Kuato]

Since it's old, sat for 2 years or more, and has an unknown service history before that, I'd be changing the oil with dino at a 3000 mile OCI for 2-3 changes. For the first 2 changes, using some cleaner (ARX, SeaFoam, MMO, whatever one you believe works best) is probably a good idea.

Once those three changes are done, if you want to try a synthetic, go for it but expect some weeping or leaking for the first 3500 miles or so. Every used vehicle I've switched over to synthetic has developed a couple of leaks, which self sealed within less than 5000 miles.

However I have not bought a used vehicle with that many miles, so your results may vary.

 

[CharBaby]

WOW, 1988!

I agree with using regular(DINO) motor oil and changing the oil/filter on a regular(3-5K miles) basis. Drive the vehicle as if you were trying to keep'er forever.

Fix the minor repairs when they occure and deffinately check/change all of the other fluids, belts, hoses, brakes etc.

 

[threeputtpar]

Originally Posted By: LeakySeals
Originally Posted By: Clevy
Originally Posted By: LeakySeals
I would try a full synthetic in that engine to see how it performs. 2 that come to mind are T6 5w40 and M1 HM 5w30/10w40.


And neither are. Funny

Anyways OP. unless you can get them on sale I wouldn't bother with a syn. The potential des exist that leaks may develop although it is less common now.
PYB,defy,max life,whichever you can find cheapest and change at 5000 miles unless there is a fuel dilution issue,then change it sooner if there is one.


And neither are what???


Uh oh, you took the bait!

 

[JasonTL]

Originally Posted By: Char Baby
WOW, 1988!

I agree with using regular(DINO) motor oil and changing the oil/filter on a regular(3-5K miles) basis. Drive the vehicle as if you were trying to keep'er forever.

Yea, older than I am

!
I intend to keep it running well for at least 5 years. I would really like to keep it going until 50, but I don't know if I'll be able to find the right parts for 25 more years of maintenance.
I really like Suburbans(10ft covered carrying capacity is awesome) and this model has the front and middle bench seats with the ability to have a third row bench(9 seats total). It also has the tailgate which I prefer over barndoors. So I can basically haul a ton of people or a ton of stuff or a 1/2 ton of each, haha.

Anyways, back to oil, heh.
Does sound like normal oil(Dino I guess y'all are calling it?) would be best. I plan to do OCI around 3k. Even if it could go 5k I'd rather be on the safe side with this engine because as was said before the service history is mostly unknown.

What is the difference between 5w30, 10w30, 15w40 and the such? I know it has something to do with outside temperature.
I think mine calls for 10w30 but I don't have the owner's manual, just a Chilton.

Also, I've read some different things about oil filters. Is there any *one* particular filter I should use or avoid?

Originally Posted By: Char Baby
Fix the minor repairs when they occur and definitely check/change all of the other fluids, belts, hoses, brakes etc.

This brings up some other questions I have but should I ask them here or in a new topic?

 

[147_Grain]

New topic in the Maintenance Section.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=postlist&Board=23&page=1

 

[Kuato]

Originally Posted By: JasonTL


...Anyways, back to oil, heh.
Does sound like normal oil(Dino I guess y'all are calling it?) would be best. I plan to do OCI around 3k. Even if it could go 5k I'd rather be on the safe side with this engine because as was said before the service history is mostly unknown.


Not a bad idea; but getting a Used Oil Analysis (UOA) after a couple of 3000 mile changes would be a good idea; if the oil is still good, why not run it a bit longer. With a lot of miles on and unknown service history, IMO it's a good idea to do several shorter changes.

Originally Posted By: JasonTL

What is the difference between 5w30, 10w30, 15w40 and the such? I know it has something to do with outside temperature.
I think mine calls for 10w30 but I don't have the owner's manual, just a Chilton.


LOTS of threads on this, and also read Bob's Oil 101 on the home page. But the basics are that the first number represents the thickness of the oil at low temps, and the last number represents the thickness of the oil at operating temp. So both the 5w30 and 10w30 will act as a 30 weight oil at operating temp. 5w30 will flow more easily when it's cold than 10w30. 15w40 will be thicker at startup and at operating temp than either the 5w or 10w30.

According to the Amsoil website for the 5.7 in 1988:

Above 0 F......10W-30
All TEMPS......5W-30

So you can use 5w30 year round.


Originally Posted By: JasonTL

Also, I've read some different things about oil filters. Is there any *one* particular filter I should use or avoid?


Most on the site will suggest avoiding Fram orange can(also known as OCOD, or orange can of death. There have been several failures or problems with this filter)

However any brand name filter (Purolator, Wix, Fram Ultra, Mann, etc) will serve just fine for a 3000 mile OCI. Plenty of discussion on filters here also, enjoy having a look around.

 

[JasonTL]

Originally Posted By: Kuato
Not a bad idea; but getting a Used Oil Analysis (UOA) after a couple of 3000 mile changes would be a good idea; if the oil is still good, why not run it a bit longer. With a lot of miles on and unknown service history, IMO it's a good idea to do several shorter changes.

Where would I have a UOA done?

Originally Posted By: Kuato
However any brand name filter (Purolator, Wix, Fram Ultra, Mann, etc) will serve just fine for a 3000 mile OCI. Plenty of discussion on filters here also, enjoy having a look around.

Thanks.
I'm probably going to do the oil change in a week or so, so I'll have some time to look around.

 

[walk23]

Defy 5W30 3K OCI's with a P1 filter.
Valvoline Complete fuel system additive
Drain and fill AT

 

[JGW]

Originally Posted By: walk23
Defy 5W30 3K OCI's with a P1 filter.
Valvoline Complete fuel system additive
Drain and fill AT


I second the Defy.

 

[JasonTL]

Originally Posted By: JGW
Originally Posted By: walk23
Defy 5W30 3K OCI's with a P1 filter.
Valvoline Complete fuel system additive
Drain and fill AT


I second the Defy.

Looking on AAP's site I can't find any Defy unless it is actually another name. I see some Quaker State that says Defy but that's 10W-30. Perhaps they just don't have it on the site or maybe you could post a link?