I've got another old V8 also, That has high mileage. And low hot idle oil pressure. I (as much as I hate to say this) have poured in a bottle of STP oil treatment. What kind of ballpark numbers would this have changed my oil viscosity. I had 5 qts of 10w30, and used 15oz of the STP. Just curious of the approximate viscosity..This was just something I had to do...sure did not want to. Have not used this [censored] since I was in high school (1975).
STP viscosity change ?
- Thread starter rustytoolss
- Start date
- Status
I would avoid STP. (Studebaker Testing Products).
A thicker oil might help. 15W40?
A thicker oil might help. 15W40?
I think you bumped it up one notch, to a 15-40. Based on your description, there is no harm in trying STP in this application.
It won't hurt, and it might help.
It won't hurt, and it might help.
On my next oil change I was thinking of going with a 10w40 or 15w40. I'm sure this engines bearings are loose. But it still runs great. Just getting oil ..like me!
I wouldnt use STP for anything... they're old company with zero innovation for a while.
Only STP thing I bought in my life was heavy duty dot 4 break fluid from gas station, it was cheapest thing they had and I didnt care at that time since the car was too old to spend good money.
Only STP thing I bought in my life was heavy duty dot 4 break fluid from gas station, it was cheapest thing they had and I didnt care at that time since the car was too old to spend good money.
Last edited:
Back in the 70's I had a car that was running on 20w-50 and a can (it came in cardboard cans then) of STP
this was an 850cc engine!
It got me to work and back for 6 months befor I sold it.
I still feel bad about taking money for that junker. But I guess the kid's father had it, and I needed it!
this was an 850cc engine!
It got me to work and back for 6 months befor I sold it.
I still feel bad about taking money for that junker. But I guess the kid's father had it, and I needed it!
STP is "Scientifically Treated Products". Studebaker bought STP in 1960/61 from Chemical Compounds Co.I believe Andy Granitelli was the previous owner (and Studebaker used him for testing and tuning their R1/R2/R3/R4 engines in 62/63,along with Salt Flats Avanti/Lark/GT Hawk runs_)
Originally Posted By: expat
Back in the 70's I had a car that was running on 20w-50 and a can (it came in cardboard cans then) of STP
this was an 850cc engine!
It got me to work and back for 6 months befor I sold it.
I still feel bad about taking money for that junker. But I guess the kid's father had it, and I needed it!
Had a '64 Impala with bad rings. The STP kept it from burning so much oil. Dumped about a can a week in the engine.
Back in the 70's I had a car that was running on 20w-50 and a can (it came in cardboard cans then) of STP
this was an 850cc engine!
It got me to work and back for 6 months befor I sold it.
I still feel bad about taking money for that junker. But I guess the kid's father had it, and I needed it!
Had a '64 Impala with bad rings. The STP kept it from burning so much oil. Dumped about a can a week in the engine.
Originally Posted By: gfh77665
I think you bumped it up one notch, to a 15-40. Based on your description, there is no harm in trying STP in this application.
It won't hurt, and it might help.
Sometimes you've gota do, what you've gotta do. Even when you don't want to. Sounds like you understand. Thanks
I think you bumped it up one notch, to a 15-40. Based on your description, there is no harm in trying STP in this application.
It won't hurt, and it might help.
Sometimes you've gota do, what you've gotta do. Even when you don't want to. Sounds like you understand. Thanks
For an older V-8, it won't hurt a bit to run the STP....in fact, if it's a bit of a beater or oil burner, then I would pour in a second can if one isn't enough to fix it.
But if you've got low oil pressure at hot idle, it's time to go with something thicker than a 10w30 on your next oil change. What's the heaviest your owner's manual recommends? My '77 Olds ran most of it's life on good old 10w40. 15w40 gives you lots of choices. A 20w50 would work in the summer in an older V-8.
Oil pumps are cheap,and easy to replace in most older V-8s, you might consider throwing one in to see what it does to help.
But if you've got low oil pressure at hot idle, it's time to go with something thicker than a 10w30 on your next oil change. What's the heaviest your owner's manual recommends? My '77 Olds ran most of it's life on good old 10w40. 15w40 gives you lots of choices. A 20w50 would work in the summer in an older V-8.
Oil pumps are cheap,and easy to replace in most older V-8s, you might consider throwing one in to see what it does to help.
Last edited:
If you assume 10.5 cSt @100C as a starting viscosity for 10w30 and 40 cSt @100C for STP then :
5 qt oil .5 qt Stp (16oz) then ending viscosity would be 11.86 cSt
4.5 qt oil and .5 qt STP then ending viscosity would be 12 cSt
Use top calculator on this .xls sheet
https://drive.google.com/file/d/0B6pXF6fWrLrgdWVxcW1VemcxVlE/view?usp=sharing
The link is to a viscosity calculator that i put together years ago just for this purpose. Im not sure about the viscosity of STP so double check that. For some reason i seem to remember 40 cSt.
If STP is 100 cSt at 100C then the numbers are as follows for 5qts / 4.5 qts and 16 oz of STP
12.89 cSt
13.15 cSt
either way it looks as if at most you may be touching the bottom end of the 40 weight range so your probably safe.
5 qt oil .5 qt Stp (16oz) then ending viscosity would be 11.86 cSt
4.5 qt oil and .5 qt STP then ending viscosity would be 12 cSt
Use top calculator on this .xls sheet
https://drive.google.com/file/d/0B6pXF6fWrLrgdWVxcW1VemcxVlE/view?usp=sharing
The link is to a viscosity calculator that i put together years ago just for this purpose. Im not sure about the viscosity of STP so double check that. For some reason i seem to remember 40 cSt.
If STP is 100 cSt at 100C then the numbers are as follows for 5qts / 4.5 qts and 16 oz of STP
12.89 cSt
13.15 cSt
either way it looks as if at most you may be touching the bottom end of the 40 weight range so your probably safe.
Last edited:
The screw driver test proves that STP is the product for you.
This is the test that should replace the 4-ball wear test when you're selecting an oil additive. If an additive can pass this test imagine what it can do for your engine. You have Andy's word on all this. What more could you possibly want?
Screw driver test.....
This is the test that should replace the 4-ball wear test when you're selecting an oil additive. If an additive can pass this test imagine what it can do for your engine. You have Andy's word on all this. What more could you possibly want?
Screw driver test.....
Originally Posted By: rustytoolss
I've got another old V8 also, That has high mileage. And low hot idle oil pressure. I (as much as I hate to say this) have poured in a bottle of STP oil treatment. What kind of ballpark numbers would this have changed my oil viscosity. I had 5 qts of 10w30, and used 15oz of the STP. Just curious of the approximate viscosity..This was just something I had to do...sure did not want to. Have not used this [censored] since I was in high school (1975).
How low is "low" hot idle oil pressure? if its enough to keep the warning light off (~5 psi) and it comes up to a decent pressure when you rev it up, I wouldn't worry too much. If its marginal, try an Xw40 oil (5w40 HDEO is a good choice, or a 10w40 high-mileage passenger car oil.)
If its turning on the warning lamp or doesn't get up above 20-30 PSI when you rev it up, consider a new oil pump. Since your signature implies it might be a Mopar... an oil pump on a big-block Mopar v8 or a slant-6 is an easy afternoon job (no dropping the oil pan required).
I've got another old V8 also, That has high mileage. And low hot idle oil pressure. I (as much as I hate to say this) have poured in a bottle of STP oil treatment. What kind of ballpark numbers would this have changed my oil viscosity. I had 5 qts of 10w30, and used 15oz of the STP. Just curious of the approximate viscosity..This was just something I had to do...sure did not want to. Have not used this [censored] since I was in high school (1975).
How low is "low" hot idle oil pressure? if its enough to keep the warning light off (~5 psi) and it comes up to a decent pressure when you rev it up, I wouldn't worry too much. If its marginal, try an Xw40 oil (5w40 HDEO is a good choice, or a 10w40 high-mileage passenger car oil.)
If its turning on the warning lamp or doesn't get up above 20-30 PSI when you rev it up, consider a new oil pump. Since your signature implies it might be a Mopar... an oil pump on a big-block Mopar v8 or a slant-6 is an easy afternoon job (no dropping the oil pan required).
Thanks for doing the math. I was never to good at it. Sounds like an xxW40 should do the trick.
BEFORE STP /Hot idle in gear @ 8psi. Hot going down the 20-45 depending on speed. Anything over 900 rpm the pressure is fine. Just didn't like seeing it that low.
After I put in the STP, I would hold 12-15psi hot at idle in gear, idling at 700rpm and 25-50psi driving.
After I put in the STP, I would hold 12-15psi hot at idle in gear, idling at 700rpm and 25-50psi driving.
MrQuackers
Site Donor 2024
STP used to sell an oil filter with two stages of filtration. I bought a few in PH 8 when on sale. Never hurt my B 20 Volvo.
Used STP when I was cutting wood for someone, ran out of bar oil, had a little left to cut, so he had STP and I poured it along the chain/bar to get the job done.
Saw someone in store buying a bunch of STP. He said he uses a few cans every oil change in his old Ford truck. Looked like he bought all off the shelf. Maybe it was on sale/clearance.
I've seen the Motor Honey and some Lucas product that seem thick like STP.
I think if I had to, maybe try 15w-40, or look into 20w-50 if I had to limp something a little longer if I had no choice.
Saw someone in store buying a bunch of STP. He said he uses a few cans every oil change in his old Ford truck. Looked like he bought all off the shelf. Maybe it was on sale/clearance.
I've seen the Motor Honey and some Lucas product that seem thick like STP.
I think if I had to, maybe try 15w-40, or look into 20w-50 if I had to limp something a little longer if I had no choice.
- Status
Similar threads
