Hello again,

I recently changed my oil about 1,000 miles ago and I have started to notice oil leaking from the head & oil pan gaskets (this is new, I check systems constantly). Here's the kicker... I went up in oil weight from a 10w-30 to a 15w-40. I have a 96' 4runner with a 3.4 V6 (230,000 miles, which was the reason for changing to thicker oil). I haven't switched from conventional to synthetic so what is the deal here?

 

What was your oil pressure before and what is it now? I would know this w/ a real gauge before switching weights. Do you mean valve cover or head gasket?

 

running a thicker oil isnt always better. thick oil when cold cant get were thin oil can get at startup. I had a good temp breakdown but my computer crashed and i havent founfd it again. iI have a toyota corolla with 265k on it i run a 5 weight oil and a4runner 3.4 with 234k on it i also run a 5 or 0 weight in it, and change it every25k miles or 1 year whichever i hit first. I got the Corolla @200k with a blown headgasket. i repaired it and swapped it over to synthetic and I drive it daily now 100 miles a day. a 5-30 oil and a 10-30 weight oil are the same when warm the benefit is from the 5 weight oil when cold at startup.

 

230k and the valve cover gaskets are just starting to leak? Man you are lucky every v6 3.4 I've worked on hasn't had over 150k on it and those things are leaking all over the place. Odd that your pan is leaking, must have been a poor FIPG job from the factory.

 

Thanks for the feedback everyone. It is the valve covers that are starting to leak, not the head gaskets (sorry). I'm switching back to 10w30 today (for better flow and less pressure), I'm going to miss the quiet 15w40 engine, but if this stops oil from leaking everywhere...

 

I don't think the thicker oil would cause the gaskets to leak if it were being pushed around at the same pressure as the thin(er) oil. But because the oil is thicker and my oil pump is still trying to move the same volume of oil, it's harder to push through the passages and would cause a higher pressure in the system. At least that's what I'm hoping is happening.

 

Try this it isnt the same one i had bit its the same article it is very lenghty but very informative. http://www.alfabb.com/bb/forums/anyt...rari-chat.html

 

So, I switched back to the "thinner" 10w-30 from 15w-40 and didn't see a drop leaking. Just finished a 16 day/2100 mile camping trip through California seeing 9000 feet altitude and the 230K 4-Runner ran like a champ. Many thanks to the advice of the previous posts.

On a side note... before the trip I changed all essential fluids (engine oil. trans oil, coolant, brake bleed and front rotors/pads). I also put on some new tires from Treadright which performed beautifully, who has amazing customer service by the way. Can't tell you how much I have learned from this forum, a big thank you to all the help!

 

isnt that what multigrade oils are for, say 15-40 15 being the viscosity when cold and 40 when warm, i dont think a 10-30 or a 10-40 would differ at start up in cold weather

 

go with a 10-40

 

Have you tried molasses? Seriously, 10W30 is the thickest I would even think about going on a 3.4 and that's only if I lived in Vegas or somewhere hot. Putting 15W40 in an engine that's designed for 5W30 is asking for it IMO. Stick with what Toyota says, they know best.

 

Fair enough. I'm thinking of switching over to Amsoil fluids. Anyone tried their 0/5-30 engine oil?

 

try searching a little bit--tons of stuff on this forum and the about oil

 

I've done quite a bit of research on oil, I became an amsoil preferred customer a couple months ago. Just wanted to hear some success stories before I pulled the trigger. Anyway, thanks to all for the help.

 

I've ran Amsoil 5w30 before and it's good stuff. Don't know about the 0w30, but I wouldn't use it personally unless you live in a cold climate.

 

I had a tech at the Toyota Dealership tell me that at the age and mileage of most of these trucks, it's no longer really what oil Toyota recommends, more so what works for you. He said lot of people run up to 20w-50.

 

My own Dad has always told me that thicker oil is better in high mileage engines, but my own experience has led me to believe that sticking with the recommended is better in most cases because there's nothing wrong with it. Maybe there's nothing wrong with using 2 or 3 grade thicker oil either, but then again maybe there is. It's hard to say for sure so I would rather not take chances. It seems in this case it may have had something to do with his valve covers leaking.

I have actually tried 10w30 in mine for a short time, but I noticed it changed the sound of my engine a little and it seemed to get an mpg or 2 less until I went back to 5w30. It's hard to provide real proof, I think it's more of a belief, but I wasn't personally impressed with the results.

 

The Ferrari, Dr Haas oil chat is a good read. Convinced me to go to a 5/30 Valvoline syn blend. And Maybe a full syn soon. And my miles are high and I have a bitty oil pump leak.

 

i run 5-30 in mine i change it every 25k. I usually do that in a year, if not i change it after a year.
10-30 and 10-40 are the same are the same at startup. if you go back and read that oil thread it explains that really well.
I also send my oil off to be tested so i have proof of what my oil is doing and what inside my engine has going on. you cant just rub it in your fingers and smell it