What are you looking to accomplish with this change? People have driven engines to many thousands of miles with conventional oil. For engine health, the greater factor appears to be oil change interval.

I would suggest using the factory recommendation of 10W30 or 5W30.

 

What I want to accomplish



I want to increase protection on cold starts, reduce oil consumption and extend oil change intervals.

The Venezuelan User´s Manual oil viscosity recommendation is pretty ambiguous, it says that depending in the ambient temps where you live you can use anything from 5w30 to 20w50. According to the temperatures where I live I can use 10w30, 15w40 or 20w50, I´m currently using the thicker viscosity but I was thinking about switching to 15w40 to increase protection in cold starts, but I was seeing that I could use 5w40 Full Synthetic and not spend much more.

 

Yes you can. Many of us - myself included - run full synthetic in our 7AFEs. But as Apples asked - what are you looking to achieve?

OP lives in Venezuela where the owners manual might call for something different than the 5w30/10w30 spec'ed in the US. I recall Australian 7AFE/4AFE calling for something similar to what OP suggested.

 

I recall Australian 7AFE/4AFE calling for something similar to what OP suggested.

That graph looks the same as Aus AE101/102s, I ran 20W50 and 20W60 for most of my old engine's life (it was a high miler though and would burn through a sump of oil in about 6,000k), been using 10W30 or 15W40 in the new one though (10W30 isn't that cheap here though)

 

A lighter oil is a good thing, to an extent. You don't want anything too light. I'd probably run a 10W-30 synthetic if it asks for 10W at your temperature. Synthetic oil does burn more, so keep an eye on the oil level, but it burns CLEANER leaving less deposits. You can definitely switch to synthetic without repercussions.

 

I mean how cold does it even get in Venezuela?

 

You should be able to switch with no problems. Coincidentally, my '95 geo prison has 283k on it, original 4afe and 3 spd auto. I switched to synthetic about 20,000 miles ago with no harmful effects. I can get synthetic cheaper than conventional occasionally-I work at an auto parts store, and sometimes they put synthetic on clearance. I pay $3 per quart then, so I buy all they have. Synthetic might help prevent the infamous stuck piston ring issue the 7afe's are known for-that alone would probably be worth the swap.

 

Since all was just overhauled switch is probably ok. The thinner oils will flow faster to bearings etc for the protection. You can watch multiple youtube videos showing the oils at 0 degrees Fahrenheit and how they perform.

Old motor I'd be very hesitant with old seals I'd be real hesitant to switch. My cars run Syn from almost day 1. My son just got handed down an '04 CRV that was on conventional for almost 200k THEN they decided to use high mileage synthetic. Front Crank seal and other points started to leak as it cleaned up a lot of junk. It's now back on conventional with some new seals in place and seeping from others seems to have stopped.

The Syn gets to all those places and flows a bit better to clean stuff up.

 

The 7A is a really robust engine, any oil you run will be fine. 5-whatever or 10W-whatever and don't worry about too much.