changed to synthetic

Synthetic flows better at all temps & especially when cold so it has its benefits. It should flow better thru the filters too so that may explain the small drop in pressure compared to dino oil

 

Once you go syn, can you go back to dino ??

 

I have used synthetics since I did my own test in 1988. Would never go back to regular on any vehicle I give a rip about. Use it in every thing down to Kohler engine on riding tractor. The cost is more than covered by longevity of oil and equipment. Don't know about pressure drop. May be due to lower viscosity. Just make sure it is approved for your application. Rotella should be just fine. I'm thinking strongly about trying the Schaffers. Heard lots of great reports here about it.

 

I side with Big Duker on this one. I wouldn't go back to a pure dino oil. Sure, one could go back to dino after using synthetic. If you are not getting good results to justify the cost, it might not be worth using synthetic. If the engine is in good shape, a synthetic will generally have a positive effect all the way around. I use full synthetics in most everything I own. I do only use a synthetic blend in my truck, but that was after some testing with a couple of brands of synthetics. The 50% synthetic blend I am using has given me the best oil sample results and is extremely cost effective. (most blends are usually only around 25% synthetic). I can get it for $9 a gallon, delivered free to the house. My Jeep Liberty Diesel, ag tractor, JD lawn mower, etc all have full synthetic in them.

A synthetic has a more uniform molecular structure, whereas a dino has a broad range of molecular sizes in the mix. It really isn't that a synthetic is "thinner", it is that the more uniform structure allows it to flow better in a broad range of temps. And it would explain the oil pressure drop you experienced. Especially since you went to a 5w40, unlike most dino DEO's that are 15w40. Thinner is relative. To be sure, a 5w40 full synthetic is more of a true 40 weight oil. The multigrade dino oils must use viscosity improvers to get to a 40 weight under operating temps, whereas the full synthetics do not need nearly the level of viscosity improvers. Keep in mind the number in front of the "w" in the oil classification is the winter flow rating and not the weight of the oil.

 

I did the same thing you did. The T5 was cheaper than dino rotella at wally world a few weeks ago. My oil pressure dropped 3 psi on the cat info display. My gut told me go back to dino 15w40 so i did. I'm pushing a million miles never been overhauled. My intervals are 10-12k miles a little below the 300 hrs cat recomends. I dont pull samples and dont have a bypass. if i did i would consider amsoil marine 15w40 FULL synthetic with extended intervals but the way i'm doing things cant justify paying twice as much for amsoil. i would never go back to a thinner 10w30 dino/syn blend like t5.... this is just my opinion..

 

I saw where you posted that it was longer than a few weeks ago probably october or november. I tested T5 just when the ambient daytime temps got below 70* wal mart had gallon jugs of T5 cheaper than T3 for a long time i think it still is. I buy all my T3 in the 5 gallon buckets though. You'll save about $10 an oil change that way. Tractor Supply is cheaper than wal mart with 5 gallon buckets but not 1 gallon jugs, figure that.. I been stocking up on 5 gallon buckets it aint gonna be under $60 a bucket much longer with a barrel of oil at $90 and prolly spiking to $100^ maybe as high as $150 like it did a few years ago