Bronco Forum - Full Size Ford Bronco Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
66 Posts
Discussion Starter #1
1) What is a good oil and weight for me to use in my 1990 high mileage Bronco (given it's history)?
2) Did the last use of Synthetic oil damage the seals, or just 'maybe' leak more due to the synthetic's consistency?

It has been in storage for the past 4 years. Last oil change was 4 years & 2,400 miles ago (Mobil 1 '15K extended performance'). I originally used Castrol GTX 10W-40. After ≈ 75k mi I changed to Castrol GTX 20W-50. I 'think' the last oil change was it's first use of synthetic oil. It does 'seem' to leak more than it used to (w/ Castrol).


It's a 1990 XLT with a 5.0L V8 engine with 168,000 miles. It does leak oil from valve covers. It is out of storage and will now be driven less than 3k mi/year (no towing).

Background if interested:
I bought it new. It spent many years towing my ski boat. I have not compression tested it, but it was VERY weak towing up hills. My boat lives on the water now, so the Bronco has not towed in 6 years. It actually has been driven very little in past 5 years.

Rear engine seal was replaced 7 yrs (15k mi) ago, but may also leak now.
It has 5-spd Automatic-Man O/D tran.


Sorry for such an 'old' question. My search found the link below which I did not feel addressed my specifics.
http://www.fullsizebronco.com/forum/showthread.php?t=177406&highlight=mileage+engine+oil
Thanks
 

·
MARBLE GARGLER!
Joined
·
11,877 Posts
I use the Mobil 1 15/50 and it does pretty good for combating oil burning, But Pennzoil 20/50 is the best for oil burning that i have ever used. as far as valve cover leaks go... replace the gaskets, straighten the v/c rails and use RTV Blacl silicone on both sides of the gaskets.
 

·
Registered
Joined
·
66 Posts
Discussion Starter #4
351W,
I am not concerned with the burning of oil, but with the best lubrication of the worn engine bearing surfaces. I have no idea if my thinking is valid, but I had thought to use thicker oil (20W-50) thinking it would fill those worn (now more clearance) bearing surface gaps.

Now reading about 'High Mileage' oils (Castrol semi synthetic and Mobil 1 Fully synthetic), I wonder if they might be a good choice. They talk about being better against the blow by the rings contaminants that are more prevalent in older engines.

Leaky valve covers is low on my Bronco 'just out of storage' fix list. I can live with that. Top rated is pull the rear brakes, replace leaky wheel cylinder and unworn 'oily' brake shoes. Also, both front windows won't go up with out 'help'. I am not looking forward to that window job! That will be another info search here. ;o)

Thanks for your reply
 

·
Registered
Joined
·
66 Posts
Discussion Starter #6 (Edited)
Gacknar,
Any comments on my thoughts of using a thicker oil (20W-50)? I'm probably most interested in hearing why my idea did not hold water, so to speak. ;o)

You do not subscribe to the 'synthetic makes it leak' camp, I take it.

I have no clue, is why I am asking.

Again, your help on my front window motor issue is extremely appreciated!
PS. I just looked at your Bronco's pics. Nice!
 

·
The Anti Yam!
Joined
·
22,680 Posts
Gacknar,
Any comments on my thoughts of using a thicker oil (20W-50)? I'm probably most interested in hearing why my idea did not hold water, so to speak. ;o)
Your engine was designed to run a 10w30, If the clearances had gotten so bad that you required a step up to 20w50, you should have noticed a drop in oil pressure.
(Mechanical gauge not meeting the minimum of 20psi @ 2,000rpm)
or
Some tapping when at full operating temperature.

If you have not seen either of these things then all you will do by using thicker oil is increase fuel consumption because thicker oil is harder to pump.

You do not subscribe to the 'synthetic makes it leak' camp, I take it.
No, in my experiance a vehichle that does not leak conventional oil, will not leak synthetic oil.

However...

An engine that does leak conventional oil, WILL leak synthetic. And due to synthetics flow properties, it MAY leak a larger volume than conventional.

But that has never stopped me from converting older engines (200,000 miles) to synthetic, and I have never experienced an increase in oil leaking, but some have.
 

·
Registered
Joined
·
66 Posts
Discussion Starter #8
Gacknar,
Thank you for your clear and direct answers. They are helpful. I will definitely stick with the 10W-30 weight.

My synthetic vs, regular decision...
Having synthetic now, makes me lean towards using synthetic again to be consistent with current oil.
The idea of 'possibly' have less oil leakage (less mess on driveway), makes me consider going back to regular oil.
The fact the Bronco will not be driven much going forward makes the synthetic's 'possible longer engine life' seem not quite as important to me.

Maybe a happy medium would be Castrol's semi synthetic hi milage 10w-30. I may give that a try.
 

·
Registered
Joined
·
2,900 Posts
If you run synthetic the biggest thing you'll see is the engine burns the oil off. Everything I've ever owned with running synthetic oil I have to add a quart every 2000 or 3000 miles or so, where with the same vehicle and conventional oil it would maintain the oil level all the way between oil changes.
 

·
Registered
Joined
·
413 Posts
I use the castrol 10w30 synthetic blend in my work fleet (16 vans and suvs). the milages are from 94k on a 07 escape to 279k on a 2006 e350, only 1 of them has a burning oil issue and thats becouse the driver hit road debris with the oil pan and locked it up...
 

·
Registered
Joined
·
66 Posts
Discussion Starter #12
I went with Castrol GTX High Mileage 10w-30. Thanks to all for the information. This community is a great resource. You are all my 'new best friends'! :eek:)

See you all on 'new' Bronco project threads.

Cheers
 
1 - 12 of 12 Posts
Top