When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Long story short I picked up a 2006 GTO with an LS2 and 40k miles. It has been stored for years and only driving 500 miles in the last 3-4 years most likely.
The oil is filthy, must be what was in there from 4 years ago. I have started it and drove it lightly around the block it sounds fine. I’m doing all fluids Friday with Mobil 1. Not driving until then.
Should i do an engine flush? I tried looking in the oil fill for sludge or anything and put my finger in there, nothing bad from what I saw. Here are pics of the oil.
If you mean putting in some kind of additive or snake oil cleaner, I say no.
If you mean running some cheap conventional oil for a hundred miles before the good oil change with Mobil 1, I say go for it if it makes you feel good. Unnecessary, I think, but it definitely won't hurt - and will do a more thorough job of getting out any water/acid that has accumulated over years of little use.
If you mean putting in some kind of additive or snake oil cleaner, I say no.
If you mean running some cheap conventional oil for a hundred miles before the good oil change with Mobil 1, I say go for it if it makes you feel good. Unnecessary, I think, but it definitely won't hurt - and will do a more thorough job of getting out any water/acid that has accumulated over years of little use.
No I'm talking about a chemical you dump in to break up oil deposits. Run that through then do a proper oil change.
I will say that desperate times call for desperate measures. In another life, I wound up with a Ford Bronco with a 351W. [sidenote: odo read 70k, suspect it was rolled back, but it also had a "quaker state" oil change sticker - yikes!] Within a month of owning it, it started losing oil pressure (as in NO oil pressure) once warmed up. I jacked the motor up and was able to drop the pan enough to finagle the oil pump and pickup tube out. It was coated with crispy sludged oil. The pickup screen was nearly blocked with - cripsy sludged oil. I cleaned that out with gasoline and scrubbing, and put it back together. It also had a valve cover leak, so I attacked that next, to find - crispy sludged oil all caked along the valve cover rail, just above the exhaust manifolds. I scraped/vacuumed that out the best I could, but obviously this engine had a lot of nastiness inside.
So I bought 5 oil filters, 5 gallons of cheap 5-30 (0-20 didn't exist then) and 5 gallons of kerosene - then mixed them together to form 10 gallons of "engine flush". I filled, ran for 15 minutes, drained, changed filter and repeated multiple times. The gunk that came out looked like liquid night every time. BUT, I did put another 50-60k miles on that truck without further issue (aside from the 351W being a pig of an engine to begin with).
Last edited by Hodgdon Extreme; May 15, 2019 at 03:44 PM.
Whoa-- Watta story! The only things I like crispy are my fries and fried chicken.
And 10-4 on the 351W! Had one in a '95 F-250. Dependable, but gutless and thirsty.
Anyway it looks like your flush system worked! But for less drastic circumstances I agree with you. Change the oil a few times and all should be well.
Auto trans fluid will EAT the sludge off of everything and dissolve it into the oil. WD-40 will also. You can use either of those things; change the oil filter, fill the new one with the alternative, drive until the oil either becomes so funkified you can't stand it (check FREQUENTLY!!!) or until you see the pressure begin to drop as the filter plugs up. Won't take long. Sometimes you'll need to change the filter several times before the oil is really ready to be refreshed.
Diesel fuel works good too, better than kerosene, but it's probably not a good idea to drive it with very much of that in it. You can drain acoupla quarts of oil, make it back up with DF, let it idle for a half hour or so, then change the oil.
As said, you can just … change the oil … and let nature run its course. But that's kinda slow, and if the motor is REALLY gunked up, will take several drain & fills of oil, which can run up quite a tab.
But, what I see on your dipstick, doesn't look too bad. Just high-mileage oil. Most likely you can just do a normal oil change to normal oil and everything will act normal.
And yeah the old 351W was pretty much a pig. About like the various GM 350s or the Xler 318 & 360 of the same period. But, if you want to scrape the bottom of the barrel, try a Frod 400M sometime.
Not a fan of engine flush or transmission flushes in general. I'd just burn through a couple of extra Mobile 1 oil & filter changes. That's what I did with my new 239,000 mile 02 Z28.
Around 200,000 miles my 91 RS started to lose some oil pressure. Short version, local Pontiac dealer (trustworthy) did an engine flush / back flush then oil change. Oil pressure returned to normal. The guess was the pick up screen had started to clog with 165,000 miles worth Quaker State sludge, that the much heavier detergent Mobile 1 had cut loose over the last 35,000 miles.
I should have been more aggressive with more frequent oil changes to get that sludge out that Mobile 1 was cutting loose.
Later mechanic (366,000 miles) pulled the valve covers and for valve cover gaskets. He insisted based on valve train condition and how clean it was the RS had nearly new replacement engine not 366,000 mile 305
I'd probably use AMSOIL engine flush if I want to flush an engine these days.
I've used Rislone engine flush (kerosene?), and had a bad experience. This was with an engine that was not the most durable to begin with (1987 Ford EXP 1.9L EFI HO). I have since done the trans fluid route, with no issues, on anything in doubt.
I vote no on the flush. Change the oil and drive it. I just picked up a 92’ RS camaro 305 TBI, from my mom. 60k miles, freaking time capsule. Oil was changed last in 2008. My dad loves Castrol. I’m going Mobil1 today in that beauty. He shook his head. I giggled.
Thanks for the info and opinions all. I decided just to change out the oil and monitor closely. I’ll be doing frequent changes as required if it gets dirty.
If for some reason it is gummed up, I’ll think about doing a flush if it really needs it after a few changes.
7 Most Reliable High-Performance Engines GM Has Ever Built
Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
Engine Flush? 
