Vintage Mustang Forums banner
1 - 20 of 24 Posts

· Registered
Joined
·
77 Posts
Discussion Starter · #1 ·
Recently, I performed an oil change on a 289 and replaced it with 10W-30. On a cold start, the oil pressure needle sits in the lower third of the gauge. After maybe an hour of casual street driving, the needle falls very low, as though there's no pressure at all. I'm wondering if the viscosity of the current oil is getting too thin once the engine is sufficiently hot and running for a while. Which oil should I use instead? Or are there other potential issues to consider? Thanks!
 

· Premium Member
Joined
·
61 Posts
I would say none. You likely have enough oil pressure as the standard is about 10lbs for every 1000 rpm,
if you like you could add a mechanical gauge to tell you exactly where your pressure is. But you are probably fine.
 

· Registered
Joined
·
77 Posts
Discussion Starter · #4 ·
Many on the forum are using Mobil 1 15w-50, and have no oil pressures issues. I’ve driven well over 200,000 miles using it in many vintage Ford engines.

Additionally , it might be a good move to get an AutoMeter oil pressure gauge and permanently install it.

Z

View attachment 860232
Thanks for the recommendation! I've been considering getting separate gauges installed to keep track of RPM and get more accurate readings of the oil pressure/temps (even though the originals are all currently functioning). I'll look into AutoMeter!
 

· Registered
Joined
·
77 Posts
Discussion Starter · #5 ·
I would say none. You likely have enough oil pressure as the standard is about 10lbs for every 1000 rpm,
if you like you could add a mechanical gauge to tell you exactly where your pressure is. But you are probably fine.
Thanks! It's good that you mentioned the standard pressure. I've been procrastinating on getting some extra gauges installed to keep a closer eye on everything. Anything you recommend?
 

· Premium Member
1966 Mustang Hardtop 289 4 Speed
Joined
·
8,604 Posts
Many on the forum are using Mobil 1 15w-50, and have no oil pressures issues. I’ve driven well over 200,000 miles using it in many vintage Ford engines.

Additionally , it might be a good move to get an AutoMeter oil pressure gauge and permanently install it.

Z

View attachment 860232
Z, what size are those gauges?
 

· Premium Member
Joined
·
15,537 Posts
I would say none. You likely have enough oil pressure as the standard is about 10lbs for every 1000 rpm,…..”
That is a generalization. Best to go by the Ford published shop manual. As it was written by the team that designed the car.

The factory specification listed in the Ford manual is 35-55 psi at 2,000 rpm.

From the 1966 Ford shop manual:
OIL PRESSURE-Hot @ 2000 rpm All Engines. .................... 35-55psi

Z, what size are those gauges?
Standard 2 1/8” (small)

Z
 

· Registered
Joined
·
45,104 Posts
Get a cheap mechanical oil pressure gauge at WalMart and screw it into your sending unit adapter by the oil filter in place of the sender. Start the engine and let it warm up. Acceptable oil pressure for the SBF is 35-55 psi at 2,000 rpm. If you engine fails to generate said pressure with 10W-30 engine oil you should investigate the causes which can include....

1. Worn engine bearings (most likely, especially if pressure DROPS as rpms are increased).
2. "Missing" front oil gallery plug.
3. Restricted oil pump pickup screen.
4. Failed gasket between pickup and pump or pump to block.
5. Stuck open oil pressure relief valve.
6. Plugged drainback holes in cylinder head(s).
7. Worn oil pump (unlikely).

I'd probably plan on dropping the pan for inspection.
 

· Registered
Joined
·
5,048 Posts
Agreed with getting a gauge first for diagnosis. I wouldn't trust the stock idiot lights for any reading further than you can throw them. That being said...low oil pressure is not going to have much to do with the viscosity of the oil...it points toward other engine problems.
 

· Registered
Joined
·
77 Posts
Discussion Starter · #12 ·
Get a cheap mechanical oil pressure gauge at WalMart and screw it into your sending unit adapter by the oil filter in place of the sender. Start the engine and let it warm up. Acceptable oil pressure for the SBF is 35-55 psi at 2,000 rpm. If you engine fails to generate said pressure with 10W-30 engine oil you should investigate the causes which can include....

1. Worn engine bearings (most likely, especially if pressure DROPS as rpms are increased).
2. "Missing" front oil gallery plug.
3. Restricted oil pump pickup screen.
4. Failed gasket between pickup and pump or pump to block.
5. Stuck open oil pressure relief valve.
6. Plugged drainback holes in cylinder head(s).
7. Worn oil pump (unlikely).

I'd probably plan on dropping the pan for inspection.
Are there any mechanical gauge options for RPM? I currently don't have a way to check that. Would be tough for me to check the oil pressure against 2k rpm.
 

· Registered
Joined
·
3,527 Posts
My preferences - YMMV

Tire Product Liquid Shelf Fluid


And my mechanical oil and temp gauges - Stewart Warner Greenline - 2 1/16

Car Vehicle Speedometer Motor vehicle Sky


John
 

· Registered
64 1/2 D Code Coupe,
Joined
·
3,584 Posts
Agreed with getting a gauge first for diagnosis. I wouldn't trust the stock idiot lights for any reading further than you can throw them. That being said...low oil pressure is not going to have much to do with the viscosity of the oil...it points toward other engine problems.
Could be just a faulty sending unit. They’re inexpensive and easy to replace. How does your engine sound at idle and at 2000 RPM? I’ve used Risilone engine cleaner to flush out my engine. I’ve been told you can do the same with ATF for 1/2 the price.
 

· Registered
Joined
·
501 Posts
Based on the filter catalog, it's supposed to be the correct replacement option for the Mighty M3600, which was on the Mustang when I bought it.
Strive to replace parts with correct ones. You have no idea what people have "made fit" over the years. The 3600 may install, but is not the correct part for a 289. That said, it is probably not your issue, but …
 

· Premium Member
Joined
·
10,006 Posts
Recently, I performed an oil change on a 289 and replaced it with 10W-30. On a cold start, the oil pressure needle sits in the lower third of the gauge. After maybe an hour of casual street driving, the needle falls very low, as though there's no pressure at all. I'm wondering if the viscosity of the current oil is getting too thin once the engine is sufficiently hot and running for a while. Which oil should I use instead? Or are there other potential issues to consider? Thanks!
Changing viscosity is a bandaid. It could be your gauge or a failing sender.
You can determine the "actual" pressure at idle and higher RPMS adding, either, a fixed mechanical gauge or a temporary gauge. It can be added in your engine compartment (my pic). I added set of mechanical gauges to the left from fender apron. After the engine is at temps, I can increase the RPMs manually and watch the action of the indicator. There are numerous postings on this subject here in the forum.
 

Attachments

· Registered
Joined
·
2,821 Posts
If you're going to add an extra oil pressure gauge don't think it has to be something fancy. A gauge and some plumbing parts from the hardware store will get you up and running quickly and cheaply and you can see what's going on without running wires or oil lines all over the place.

Gauges in the dash are nice, but if you just need to see what's going on you don't necessarily have to do all of that work.
Vehicle Motor vehicle Automotive tire Hood Car
 

· Premium Member
Joined
·
1,769 Posts
I'm running the VR1 10W30 with a Motorcraft filter and stock replacement oil pump, not a high pressure unit. At startup she's pegged right at 60psi per my AutoMeter gauge. Once warmed up it hovers 50-60 psi consistently.
 
1 - 20 of 24 Posts
Top