engine oil

aleebee156 said:

whats everyones thoughts on switching to synthetic after 180,000 miles of using conventional? Just curious. Im not thinking of changing, because the conventional has been great to me, but curious your thoughts on any issues changing to synthetic...

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If it ran the first 180k itll run the next 180k. Just my opinion. Some oils put up better numbers than others, but youre not driving an indy car. Im sure somebody will chime in shortly and have a different opinion, its just oil though.

I switch the synthetic at about the same time period... doesn't hurt anything... some say synthetics can break up conventional and cause leaks, but not in my various 3 that all switched.

...I still don't get the often synthetic hate it's like a Mcdonald big Mac meal more if price is the main turn off (agree with longer than 3k internals).

I've run synthetics off and on for the last 70k miles and haven't had any leakage issues crop up that weren't already evident. I generally run a 15w40 in the summer because I get it for free, but in winter I go to Rotella T6 5W40 because it lessens or eliminates the cold start lifter noise I have and keeps my operating temp oil pressure in the range I like. The engine has 306k on it and needs the 40 weight to maintain approximately 20 psi oil pressure at operating temp.

I'm all for synthetics if you plan on running extended oil drain intervals, provided you do it with the proper oil testing to verify that you aren't exceeding the oil's capabilities. That's the only way that running them makes sense. Running a top dollar synthetic and changing it at 3k miles is just like throwing money out the window. Any API certified oil will do that, no matter who makes it.

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aleebee156 said:

whats everyones thoughts on switching to synthetic after 180,000 miles of using conventional? Just curious. Im not thinking of changing, because the conventional has been great to me, but curious your thoughts on any issues changing to synthetic...

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I've always switched to synthetic, because I always run Rotella (synthetic), and almost always have a used vehicle. I've never burst into flames over it.

Synthetic is of little use to our vehicles unless you are wanting to go longer on an oil change. Today's conventionals changed at the proper intervals are more than satisfactory for our vehicles for the most part. A used oil analysis is the best way to determine if your oil is doing its job.

i don't know. i wouldn't just because regular oil had been fine for me

Zinc has been removed from oil in the last few years because the EPA says it messes uo the cat cinvertors. Some deisel oils still have it, but even Rotella has cut most of it out. Motorcraft deisel oil probabky still has it since it says not to use it on gasoline engines with convertors on them. I purposely bought some to use in my Metro, just to spite the tree huggers, lol. I have always used 15/40 or 20/50 in all tyoes oils, normal, mixed, or full synthetic. Synthetic oil will clean the sludge out of your engine so if your engine is nasty inside, you may want to change the filter early at least. STP oil treatment has lots of zinc in it so adding a bottle should bring the low or no zinc oil back to old levels. Not so needed fir roller cams but the flat tappet cams do need it.

MarkZ28 said:

Zinc has been removed from oil in the last few years because the EPA says it messes uo the cat cinvertors. Some deisel oils still have it, but even Rotella has cut most of it out. Motorcraft deisel oil probabky still has it since it says not to use it on gasoline engines with convertors on them. I purposely bought some to use in my Metro, just to spite the tree huggers, lol. I have always used 15/40 or 20/50 in all tyoes oils, normal, mixed, or full synthetic. Synthetic oil will clean the sludge out of your engine so if your engine is nasty inside, you may want to change the filter early at least. STP oil treatment has lots of zinc in it so adding a bottle should bring the low or no zinc oil back to old levels. Not so needed fir roller cams but the flat tappet cams do need it.

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I run rotella 10w30 and a half bottle of STP per oil change, for the lack of zinc like you stated.

Just out of curiosity, you personally put more zinc in for better startup lubrication on older engines or do I have it wrong why you personally do?

SLmateo said:

Just out of curiosity, you personally put more zinc in for better startup lubrication on older engines or do I have it wrong why you personally do?

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Zinc used to be in oil in high concentrations. It helped flat tappet lifters like ours live.

As everything went roller or OHC, there was less need for it, so it was removed to help CAts live longer. Those of us with older engines are stuck needing more zinc than most oil can provide.

FWIW, 1200 ppm is considered safe for a flat tappet cam.

Shell Rotella T 5w40 VOA ('old' CJ-4 formulation)
Zn 1252 ppm
P 1105 ppm
Mo 61 ppm

Shell Rotella T6 5w40 VOA ('new' CJ-4 formulation)
Zn 1264 ppm
P 1147 ppm
Mo 59 ppm