When I first got my 1986 Camaro IROC Z it was no doubt neglected. The oil was black when I first got it. Now 8 years later it's been much better taken care of. For the first few years I owned it, I ran conventional oil. When I started to drive it more, I switched to Valvoline High Mileage Synthetic Blend and have been using that for the last 2 years and I now change oil every 3 months. I have zero leaks in 8 years of ownership, May car has even sat a ton lately and no leaks (I do try to fire it up everyday) and not a single drop of oil. When I had the transmission rebuilt a few years ago, the owner of the transmission shop was surprised it didn't leak at all even when it was there for close to two weeks.
Would it be safe to make the switch to Full Synthetic High Mileage oil? Or should I simply stick with synthetic blend?

I know full synthetic doesn't cause leaks on it's own despite the old myths still persisting. But I know it's a much better cleaner compared to conventional oil and can expose leaks that were covered in sludge, after the sludge is cleaned away.

My car has 125K+ miles.

 

Yes. My '86 TA has had synthetic since break-in. Due to the flat-tappet cam in pre-87 cars, I've switched to the "high-mileage" formulation since the analysis indicated greater EP additives in the mix (more zinc).

 

Yep. When I got my car at 120K, I went full Mobil 1 synth in the engine, trans, and rear. No issues. It wasn't the high mileage stuff, it was the regular Mobil 1.

And actually full synth did have problems with leaks on older cars. They have revised the formulas since then.

 

Right after I got my car in 2017 with 78k on it I replaced all fluids with synthetic, Mobil 1 High Mileage engine oil, Royal Purple in the diff, Valvoline Max Life High Mileage in the trans and Lubegard power steering fluid. No issues to report with the synthetic fluids.

 

I switched to synthetic at 115k miles in my GMC Safari. Went to HM synthetic at 145k miles. Presently at 165k miles. No oil related issues that I can tell. The engine is well on it's way to being worn out anyways, so MEH.

 

My daughters Toyota Solara w/ 352K miles on it, I've decided to use high mileage oil for the seals. but haven't worried if it is synthetic or not. just a guess, nothing scientific.
Got me thinking that maybe some high mileage oil may be good for the Formula seals.

What are we really talking about here anyway?

Oil pan, rear main, timing chain cover - did I miss anything? (valve covers, but those are easy to replace)

 

I guess timing chain and rear main? I always hear about people developing leaks on high mileage cars and it drips in your driveway. I know SBCs tend to be better than most when it comes to leaks but I have seen a few with trouble.

 

At 215K my rubber valve cover gaskets on my 07 G35 where as hard as a brick. They were seeping oil onto the exhaust. I got the car with 130K on it and switched to synthetic at that time. I run Mobil One or Penzoil Platinum with a longer oil filter for a Titan and change it every ~7,500 miles. I also run a bottle of Techron in the fuel before every oil change. I think the results speak for themself.

 

nice and clean! Good idea to run the Techron just before oil change. Hadn't thought about doing that before. I presume you're doing this to keep it from tainting the oil?

 

That doesn't look like 200,000 miles worth of sludge. That's a testament to good quality, clean oil with good flow thanks to the designers and your driving habits. The oil clenliness is helped by a good filter, but may be more attributable to good fuel control since combustion deposits are frequently what contaminates oil. It also appears that the engine gets up to full running temperature and sustains it for long periods, which helps oil flow and its ability to clean.

The real test of the oil is how much wear occurs in that 50-60 feet of timing chain on the front of the Nissan. I'm guesing that you haven't had too much trouble with that yet, judging by the general condition shown.

 

I not the same poster but I've been running Techron or BG (when I worked as a lube tech) just before or just after every oil change. It helps keep the valves in the heads clean. Keeps carbon off of them.

 

Still the factory ones, still sees 7,500 rpm at WOT atleast once a day. I am a firm believer in a WOT run a day keeps the mechanic away.

Car did not even get plugs changed in it until 177K. Changed them because I felt bad they had never been changed and thought it might idle more smoothly. No noticeable change, lol.

 

I use MOBIL 1 Synthetic oil, and ONLY Mobil 1 Synthetic Oil.

I have not used the "high mileage formula", but generally use 15w50 in my small block Chevrolet engines. When I had my last GTA apart at around 100k mi, it looked brand new inside.

 

There are better oils on the market now but Mobil One still gets the job done. Penzoil Platinum has better test results than Mobil One. I used whichever one was on sale with either a Mobil One or Wix XP filter.
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I use full synthetic only. Even if on the bottle says change every 7-10k miles now, I’ll still change it at 3k or every few months, whichever comes first. Haven’t tried Royal Purple yet and there are those who swear buy it, so I might have to give it a go one of these days.

 

They do it b/c it's a religion. It would look like that without the bottle of snake oil. :yesnod:

HAVE A LOOK HERE

 

Actually they didn't look like that when I did the plugs. They had carbon buildup and were in general fairly sooty and nasty. Remember VVT engines use cam phasing for internal EGR. Not nearly as bad as my other Infiniti but not clean like that either.

 

Did you look at the link I posted for you?

 

This is a weird, but typical post process for Fast355. Maybe I've missed something;
(See pics in post 9 of the cams/head and another if the intake runner)
What's Techron use got to do with the cleanliness of the head/cams? (photo #1). That pic is ALL about decent oil and doing oil changes...not Techron.

Wait...say what!? First, what didn't look like what "when you changed the plugs"? What does changing the plugs have to do with anything in this thread? Were you talking about the intake valves? Is that what "had carbon build up and were in general fairly sooty and nasty."? Because did you see the intake valves in the pics that I posted of intake valves that never saw Techron?
When did you start your your Techron regimen? When you bought the car and "switched over to synthetic"? Did you run it 47k miles, then change spark plugs, somehow look at the valves, and then in the next 38k, they cleaned themselves up? The Techron worked after 177k...but not so much, before? Did the Techron, after 177k clean the intake valves to about the same cleanliness as the pics I shared of nothing-special-gas, no-additives, engines? Please elaborate with a clearer timeline! This is quite an interesting tale, so far.....


WTF does that have to do with the price of milk?? EGR function is happening either way that it's regulated. What's that got to do with pictures of cam shafts and intake runners? :bigears:

 

I use Penzoil Platinum 5W30 in my IROC
I use Mobil 1 5W30 in my Corvette.

Neither are particularly high miles, but no issues related to internal engine health and only a few seeping spots that you can tell when you are under it, but it doesn't drip. Not bad for a 32 year old motor.

 

Multiple things going on should have been more clear. I switched to synthetic in the ~130K range.

I changed the plugs at 177K. I mentioned it because in order to change the plugs I had to pull the plenum. The valves were coated in a gummy looking carbon buildup at 177K. I started the Techron regime at 177K. Went into the engine again around 215K to change the valve cover gaskets. The picture of the clean ports and valves was taken when the plenum was off to do the valve cover gaskets. No change in fuel or driving habits other than the regular doses of Techron. My point with the way Nissan does the EGR using VVT is the reason for the carbon buildup I saw. The added detergent of the Techron seems to have eliminated the buildup. The only other change during that time period was headers and high flow cats but they literally went on the car the day before the valve cover gaskets were changed.

 

Wow....that was way, WAY more clear and understandable. Thanks for that good post.

That Techron was pretty effective at valve cleaning (in that engine) then; 5 applications.